Witnesses say Yemen's capital was mostly quiet late Tuesday after Vice President Abed Rabbo Mansour Hadi called for a cease-fire to end clashes that have killed more than 60 people in recent days.

The Associated Press says the vice president negotiated a truce between government forces and dissident troops with the help of several foreign ambassadors. The opposition troops are loyal to Ali Mohsen al-Ahmar, a general who defected to the opposition months ago.

Until a calm set in, Tuesday marked the third straight day of violence in Sana'a. Security forces clashed with dissident troops and anti-government protesters, killing at least nine people before the call for a cease-fire.

Witnesses say machine gun fire and heavy shelling rocked the capital. Some shells fell on an anti-government protest camp called Change Square.

Yemen's youth-led protest movement stepped up demonstrations last week, angry after President Ali Abdullah Saleh instructed his deputy to negotiate a power-sharing deal. Many called the move the latest of the president's delaying tactics as he avoids demands to step down.

Diplomats and Yemeni politicians are trying to revive a long-stalled transition plan under which Mr. Saleh would hand over power. U.N. envoy Jamal bin Omar and the secretary-general of the six-nation Gulf Cooperation Council arrived in Sana'a Monday and were expected to join the talks.

Mr. Saleh has agreed to the GCC proposal three times since April. However, in each case, he backed out before a deal could be signed.

Meanwhile, the International Organization for Migration says Yemen's violence over the past few days has complicated efforts to evacuate several thousand mostly Ethiopian migrants who are stranded near the Saudi border with Yemen.