Police guard Place de la Sorbonne in front of La Sorbonne University in Paris after it was evacuated, March 11, 2006. French riot police used tear gas to break up a three-day sit-in at the university on Saturday as angry students threatened a mounting challenge to government labour reforms. +++ FRENCH LAW REQUIRES THAT FACES OF LAW ENFORCEMENT OFFICERS ARE MASKED IN PUBLICATIONS WITHIN FRANCE +++ REUTERS/Benoit Tessier