Public school teachers are blocked by army soldiers as they shout slogans during a demonstration to demand a pay rise in Sanaa April 3, 2011. Yemeni President Ali Abdullah Saleh called on opponents demanding he step down to end weeks of street protests on Sunday, in a further sign the veteran ruler has no intention of resigning soon. REUTERS/Khaled Abdullah (YEMEN - Tags: POLITICS CIVIL UNREST EDUCATION MILITARY EMPLOYMENT BUSINESS)