International peace envoy Kofi Annan says Syrian President Bashar al-Assad has agreed to begin withdrawing forces from opposition protest hubs and complete the pullout by April 10.

Mr. Annan announced the agreement on Monday in a briefing to the U.N. Security Council via videoconference from Geneva. Diplomats later quoted Mr. Annan as saying the Syrian president agreed to several “immediate” steps including a cessation of troop movements toward population centers and the start of a withdrawal of soldiers and heavy weapons already in such areas.

Annan spokesman Ahmad Fawzi told VOA that the agreement calls for Mr. Assad to complete those steps by April 10 and requires Syrian rebel forces to abide by a cease-fire within 48 hours of that deadline.

U.S. Ambassador to the the United Nations Susan Rice said Washington is skeptical about the prospects of Syria's government meeting the deadline. She said Mr. Assad has made and broken promises repeatedly in recent months and followed such commitments with a “massive intensification of violence.”

The cease-fire proposal is part of a peace plan drafted by Mr. Annan last month and later endorsed by a U.N. Security Council statement. The U.N.-Arab League envoy's plan originally did not set any deadlines for Syrian government or rebels forces to comply.

Syria's U.N. Ambassador Bashar Ja'afari told reporters that his government is committed to the success of Mr. Annan's mission. He said Damascus also expects Mr. Annan to contact those parties who initiate, sponsor and supply weapons to armed terrorist groups that Syria blames for the revolt.

Ja'afari also criticized Sunday's meeting in Istanbul of more than 70 nations opposed to Mr. Assad's crackdown on the uprising, calling the “Friends of the Syria” coalition an enemy of Syria.

He condemned a plan by Gulf members of the coalition to pay the salaries of Syrian rebels and a U.S. offer to send communications equipment to Syrian opposition activists as “an act of war.” He also criticized former Syrian ally Turkey for hosting the meeting of the anti-Assad coalition.

Earlier Monday, Russian Foreign Minister Sergei Lavrov reiterated Moscow's opposition to ultimatums on the Assad government, a longtime Russian ally and purchaser of Russian weapons.

Speaking on a visit to Armenia, Lavrov said “artificial deadlines rarely help matters” and should be imposed on all sides of the conflict. But he also said the Syrian government should move first to stop the fighting.

International Red Cross chief Jakob Kellenberger said Monday he was returning to Syria to try to secure agreement on a daily two-hour pause in violence to allow humanitarian workers to reach civilians affected by the conflict.

Syrian rights activists say attacks by government and rebel forces across the country killed on Monday at least 18 people, most of them civilians.

The United Nations says more than 9,000 people have been killed in Syria since the uprising began a year ago.