Yemeni government troops have killed six suspected al-Qaida militants in overnight clashes in southern Abyan province.

Local officials said Saturday at least three gunmen were wounded in the fighting in the provincial capital, Zinjibar.

The killings came a day after Yemeni forces renewed shelling in the country's second largest city of Taiz, leaving at least 11 civilians dead. News reports said pro-government forces opened fire near Freedom Square, the site of ongoing protests against President Ali Abdullah Saleh.

In a statement Saturday, the U.S. State Department said it was “deeply troubled” by reports of attacks against civilians in Taiz and called on all sides to exercise maximum restraint. The statement said that “if President Saleh cares about Yemen's future and the well-being of the Yemeni people, he must immediately initiate a full transfer of power that allows early presidential elections to be held.”

The turmoil coincides with a visit by U.N. envoy Jamal bin Omar in Yemen to try to convince the president to accept an initiative that calls for him to step down.

The Yemeni leader has repeatedly indicated he would accept the terms of the agreement, which was brokered by the Gulf Cooperation Council , but each time has backed away without signing the plan.

For months, opposition activists have held demonstrations calling on Mr. Saleh to resign. The president's supporters frequently have held rival rallies coinciding with the opposition protests.

Mr. Saleh could face increased pressure from the European Union next week to accept the GCC initiative. French Foreign Minister Alain Juppe said the EU is set to discuss a plan that would freeze Mr. Saleh's assets if he does not agree to end his 33-year rule.