Greek Prime Minister Alexis Tsipras (L-R), Italian Prime Minister Matteo Renzi and German Chancellor Angela Merkel attend a European Union leaders summit in Brussels, Belgium, June 25, 2015. REUTERS/Yves Herman
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Greek Prime Minister Alexis Tsipras (L) talks to German Chancellor Angela Merkel next to Italian Prime Minister Matteo Renzi (C) at a European Union leaders summit in Brussels, Belgium, June 25, 2015. REUTERS/Yves Herman

Greek Prime Minister Alexis Tsipras speaks to media on arrival at the European Union (EU) Council headquarters for an EU leaders summit in Brussels, Belgium, June 25, 2015. The European Union leaders summit on migration, the long-term future of the euro zone and renegotiating Britain's membership terms, has been overshadowed by the looming Greek debt crisis. REUTERS/Darren Staples TPX IMAGES OF THE DAY

Greek Prime Minister Alexis Tsipras speaks with Cyprus President Nicos Anastasiades (L) and European Parliament President Martin Schulz (C) amongst European leaders as they arrive at a family photo at the EU Council headquarters during a European Union leaders summit in Brussels, Belgium, June 25, 2015. REUTERS/Philippe Wojazer 

German Chancellor Angela Merkel (R) speaks with European Parliament President Martin Schulz (L) and French President Francois Hollande (C) as they leave a family photo at the EU Council headquarters during a European Union leaders summit in Brussels, Belgium, June 25, 2015. REUTERS/Philippe Wojazer 

International Monetary Fund Managing Director Christine Lagarde (L) looks at Greek Finance Minister Yanis Varoufakis (R) during a Eurozone finance ministers emergency meeting on the situation in Greece in Brussels, Belgium June 25, 2015. Greece's international creditors gave Athens an ultimatum to come up with a credible reform plan on Thursday warning they would otherwise put their own proposals to euro zone finance ministers for approval, a euro zone official said. REUTERS/Philippe Wojazer 

From L-R: Italian Finance Minister Pier Carlo Padoan, Eurogroup President Jeroen Dijsselbloem, International Monetary Fund Managing Director Christine Lagarde, Irish Finance Minister Michael Noonan and French Finance Minister Michel Sapin attend a Eurozone finance ministers emergency meeting on the situation in Greece in Brussels, Belgium June 25, 2015. Greece's international creditors gave Athens an ultimatum to come up with a credible reform plan on Thursday warning they would otherwise put their own proposals to euro zone finance ministers for approval, a euro zone official said. REUTERS/Philippe Wojazer TPX IMAGES OF THE DAY

Greece's Prime Minister Alexis Tsipras (L) speaks with European Union Foreign Policy Chief Federica Mogherini as they arrives for a family photo at the EU Council headquarters during a European Union leaders summit in Brussels, Belgium, June 25, 2015. REUTERS/Philippe Wojazer 

Greek Prime Minister Alexis Tsipras (L), European Commission President Jean Claude Juncker (C) and German Chancellor Angela Merkel attend a European Union leaders summit in Brussels, Belgium, June 25, 2015. REUTERS/Yves Herman

(L-R) Danish Prime Minister Helle Thorning Schmidt, Polish Prime Minister Ewa Kopacz, German Chancellor Angela Merkel and Lithuanian President Dalia Grybauskaite attend a European Union leaders summit in Brussels, Belgium, June 25, 2015. REUTERS/Yves Herman

Greek Prime Minister Alexis Tsipras (L) is welcomed by European Commission President Jean-Claude Juncker ahead of a meeting in Brussels, Belgium June 24, 2015. Tsipras flew to Brussels to meet Greece's international creditors on Wednesday to try to bridge gaps on key elements of the proposals made by his left-wing government to shore up state finances in return for vital loans. REUTERS/Julien Warnand/Pool
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European Central Bank President Mario Draghi leaves a Eurozone finance ministers emergency meeting in Brussels, Belgium June 24, 2015. Greek Prime Minister Alexis Tsipras wrestled with creditors demanding changes to his proposed tax and reform plans on Wednesday in a last-minute race to clinch a deal to which euro zone finance ministers could agree. REUTERS/Yves Herman

Greek Finance Minister Yanis Varoufakis (L) and Euclid Tsakalotos, Chief Economics spokesman of the Greek government attend a Eurozone finance ministers emergency meeting in Brussels, Belgium June 24, 2015. Greek Prime Minister Alexis Tsipras wrestled with creditors demanding changes to his proposed tax and reform plans on Wednesday in a last-minute race to clinch a deal to which euro zone finance ministers could agree. REUTERS/Yves Herman

International Monetary Fund Managing Director Christine Lagarde arrives at a Eurozone finance ministers emergency meeting in Brussels, Belgium June 24, 2015. Greek Prime Minister Alexis Tsipras wrestled with creditors demanding changes to his proposed tax and reform plans on Wednesday in a last-minute race to clinch a deal to which euro zone finance ministers could agree. REUTERS/Yves Herman

French Finance Minister Michel Sapin (L) passes behind Greek Finance Minister Yanis Varoufakis (C) and Chief Economics Spokesman of the Government of Greece Euclid Tsakalotos (R) prior to a Eurozone finance ministers emergency meeting in Brussels, Belgium, June 24, 2015. Greek Prime Minister Alexis Tsipras wrestled with creditors demanding changes to his proposed tax and reform plans on Wednesday in a last-minute race to clinch a deal to which euro zone finance ministers could agree. REUTERS/Philippe Wojazer 

Greek Prime Minister Alexis Tsipras leaves the European Commission headquarters after a meeting with the European Commission, the International Monetary Fund (IMF), the European Central Bank (ECB) and the bloc's rescue fund in Brussels, Belgium June 24, 2015. Tsipras wrestled with creditors demanding changes to his proposed tax and reform plans on Wednesday in a last-minute race to clinch a deal to which euro zone finance ministers could agree. REUTERS/Yves Herman
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European Commission President Jean-Claude Juncker (L) talks with International Monetary Fund (IMF) Managing Director Christine Lagarde (R) during a meeting with officials before the arrival of Greek Prime Minister Alexis Tsipras in Brussels, Belgium, June 24, 2015. European Union leaders will not negotiate financing-for-reforms with Greece at their summit on Thursday and want Athens to reach a deal with euro zone finance ministers on Wednesday even if talks are to take all night, a senior EU official said. REUTERS/Virginia Mayo/Pool 

Greek Prime Minister Alexis Tsipras (L) is welcomed by European Commission President Jean-Claude Juncker for a meeting ahead of a Eurozone emergency summit on Greece in Brussels, Belgium June 22, 2015. The European Union welcomed new proposals from Tsipras as a "good basis for progress" at talks on Monday where creditors want 11th-hour concessions to haul Athens back from the brink of bankruptcy. REUTERS/Yves Herman
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Greek Prime Minister Alexis Tsipras (front) is welcomed by European Commission President Jean Claude Juncker for a meeting ahead of a Eurozone emergency summit on Greece in Brussels, Belgium June 22, 2015. The European Union welcomed new proposals from Greek Prime Minister Alexis Tsipras as a "good basis for progress" at talks on Monday where creditors want 11th-hour concessions to haul Athens back from the brink of bankruptcy. REUTERS/Yves Herman

Greek Prime Minister Alexis Tsipras (R) and Finance Minister Yanis Varoufakis (C) are welcomed by European Council President Donald Tusk ahead of a meeting during a Eurozone emergency summit on Greece in Brussels, Belgium June 22, 2015. A new Greek offer for a cash-for-reforms deal raised hopes of an agreement as euro zone leaders prepared for an emergency summit on Monday, with EU officials welcoming the proposals as a "good basis for progress" to avert a default by Athens. REUTERS/Eric Vidal 

(L-R) French President Francois Hollande, Greek Prime Minister Alexis Tsipras and Spanish Prime Minister Mariano Rajoy attend a Eurozone emergency summit on Greece in Brussels, Belgium, June 22, 2015. REUTERS/Yves Herman

(L-R) German Chancellor Angela Merkel, International Monetary Fund (IMF) Managing Director Christine Lagarde, European Commission President Jean-Claude Juncker, European Central Bank President Mario Draghi, French President Francois Hollande, Greek Prime Minister Alexis Tsipras and Spanish Prime Minister Mariano Rajoy attend a Eurozone emergency summit on Greece in Brussels, Belgium, June 22, 2015. REUTERS/Yves Herman
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International Monetary Fund (IMF) Managing Director Christine Lagarde speaks before leaving the European Commission after a meeting ahead of a Eurozone emergency summit on Greece in Brussels, Belgium late June 22, 2015. A new Greek offer for a cash-for-reforms deal raised hopes of an agreement as euro zone leaders prepared for an emergency summit on Monday, with EU officials welcoming the proposals as a "good basis for progress" to avert a default by Athens. REUTERS/Charles Platiau 

Eurogroup President Jeroen Dijsselbloem holds a news conference after a Euro zone finance ministers emergency meeting on Greece in Brussels, Belgium June 22, 2015. Euro zone finance ministers gathered in Brussels on Monday ahead of an emergency summit of euro zone leaders designed to reach a last minute deal to pull Athens back from the brink of bankruptcy. REUTERS/Yves Herman

Germany's Chancellor Angela Merkel holds a news conference after at a Eurozone finance ministers emergency meeting on Greece in Brussels, Belgium June 22, 2015. A new Greek offer for a cash-for-reforms deal raised hopes of an agreement as euro zone leaders prepared for an emergency summit on Monday, with EU officials welcoming the proposals as a "good basis for progress" to avert a default by Athens. REUTERS/Eric Vidal

German Chancellor Angela Merkel (L) talks with French President Francois Hollande after their bilateral meeting during a Eurozone emergency summit on Greece in Brussels, Belgium, June 22, 2015. REUTERS/John Thys/Pool 

EUROZONE-GREECE TIMELINE - Charts Greece's 10-year government bond yield and average credit rating for the country since 2009. (SIN06)