“The deadline is now,” Annan’s spokesman Ahmad Fawzi said in Geneva. “We expect him to implement this plan immediately.”

Removing any ambiguity about the ceasefire terms of a six-point peace plan that Assad has said he accepts, Fawzi said it was up to the Syrian military to move first and show good faith by withdrawing tanks, big guns and troops from cities.

However, Syrian artillery hit parts of Homs city and at least five people were killed in clashes around the country yesterday, opposition activists said.

Activists appealed for more mass demonstrations yesterday to denounce Arab states for “abandoning” protesters by not backing calls to send arms to rebels fighting Assad’s forces.

UN-Arab League peace-broker Annan’s cease-fire appeal came as monitors said shells rained down on Homs, a main rebel bastion which has been the focus of much of President Assad’s year-long crackdown on anti-regime protests.

“We expect him to implement this plan immediately. Clearly we have not seen a cessation of hostilities on the ground. This is our great concern,” the spokesman said in Geneva, adding the “deadline is now” for Assad’s regime to end all violence.

The plan calls for a commitment to stop all armed violence, a daily two-hour humanitarian cease-fire, media access to all areas affected by the fighting, an inclusive Syrian-led political process, a right to demonstrate, and release of arbitrarily detained people.

“I can’t tell you what the next steps will be if they don’t stop now,” Annan’s spokesman said, adding however that Annan was due to brief the UN Security Council on Monday and “we will take it from there.”

Annan is also working to convince the Syrian opposition to “lay down their arms and start talking,” he said. State-run news agency SANA said on Thursday that “President Assad... has informed Annan that Syria approves the plan (the envoy) submitted but had made remarks about it.”

Assad would “spare no effort” for the success of Annan’s six-point plan but said the proposal would only work if “terrorist acts” by foreign powers stopped.

A Britain-based monitoring group said at least five people were killed yesterday as the regime however continued a crackdown that the UN says has seen more than 9,000 people killed in the past year.

A sniper shot dead a civilian in the city’s Khaldiyeh district, and two others were killed when their car was fired upon elsewhere in the province of Homs, said the Syrian Observatory for Human Rights.

Security forces set alight four houses during raids in Jarjanaz, near the town of Maaret Al-Numan in Idlib province, where a sniper killed a 45-year-old civilian, it added.

At Irbin, near Damascus, a soldier was killed in an attack on a military checkpoint.

Fierce fighting was also reported in the provinces of Hama, in central Syria, and Deir Ezzor in the east, said the Local Coordination Committees, which organizes anti-regime protests.

An Arab League summit in Baghdad on Thursday called for an end to the crackdown, for the opposition to unite and for parties to the conflict to launch a “serious national dialogue.”

The opposition had urged a harsher statement backing Qatar and Saudi Arabia, who have called for Assad to step down and for rebels opposing his regime to be supplied with arms. But Iraqi Prime Minister Nuri Al-Maliki said that giving weapons to either side “will lead to a regional and international proxy war in Syria.”

In response, Syrian activists blocked a street and burned tires late Thursday in Damascus to protest the “failure of the Arab League,” according to a video posted online.

Internet-based activist group The Syrian Revolution 2011, one of the main motors of the uprising, called for more protests yesterday against the Arab world’s inaction. “The Muslims and the Arabs have abandoned us... but God is with us... and our determination will carry us to victory,” the group said on Facebook.