Diplomats say international peace envoy Kofi Annan has urged the U.N. Security Council to give Syrian President Bashar al-Assad 10 days to fully implement a cease-fire in his year-long crackdown on dissenters.

The diplomats say Annan made the appeal to council members on Monday in a closed-door briefing via videoconference from Geneva. They quote Annan as saying the Syrian president has agreed to begin partial implementation of a cease-fire by April 10 and complete the move 48 hours later.

Annan's proposed cease-fire calls for the Syrian government to take the first step in ending the conflict by curtailing troop movements in opposition protest hubs, withdrawing heavy weapons and starting a pullout of forces.

The proposals are part of a peace plan drafted by the U.N.-Arab League joint envoy last month and later endorsed by a U.N. Security Council statement. The plan did not set deadlines for Syrian government or rebels forces.

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 killed at least 11 people on Monday across the country.

On Sunday, the United States and more than 70 other countries opposed to Syrian President Assad's crackdown pledged to send money and communications equipment to opposition groups inside Syria.

Syrian state media denounced the Istanbul conference as a gathering of the “enemies of Syria.”

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