At least 33 people were killed Friday across Syria, opposition activists said, as United Nations-Arab League envoy Kofi Annan urged President Bashar al-Assad to immediately implement a ceasefire, dpa reported.
Annan's plea came as activists reported heavy shelling in the central province of Homs and the northern area of Idlib near the Turkish border.
"The deadline is now," said Annan's spokesman Ahmad Fawzi, three days after announcing that al-Assad had accepted the peace plan.
"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," Fawzi said in Geneva.
Annan's plan calls for a ceasefire, to be monitored by UN observers; access to humanitarian services; and talks between the government and the opposition.
Fawzi said the government has to take the first step in stopping the violence, being the stronger party in the conflict.
He said Annan was scheduled to address the UN Security Council on Monday about his latest mediation efforts, which last week took him to Russia and China, Syria's main allies.
Annan is also scheduled to send one of his team members to Turkey soon to hold talks with the Syrian opposition. He is set to visit Saudi Arabia and Iran to gain more support for his peace plan, Fawzi said.
Al-Assad said he would "spare no effort" for the success of Annan's plan, state-run SANA news agency reported Thursday, but said the proposal would only work if "terrorist acts" by foreign powers stopped.
Meanwhile, activists based in Homs said at least 15 people, among them a 12-year-old boy, were killed in heavy shelling. In Idlib, four people were killed near the village of Maaret al-Namaan, the Local Coordination Committees said.
Security forces set ablaze four houses during raids in Jarjanaz, near Maaret al-Namaan, where a sniper killed a 45-year-old civilian, the group claimed.
In Deir al-Zour, near the Syrian-Iraqi border, seven people died in shelling and clashes between opposition rebels and the army, the London-based Syrian Observatory for Human Rights said.
In areas near the capital Damascus, six people were killed when security forces fired at anti-regime protesters.
An Arab League summit in Baghdad Thursday called for an end to the crackdown and for the opposition to unite and launch a "serious national dialogue."
The summit's final statement angered the opposition, which has been calling for a harsher stand against al-Assad's government.
"This is a statement that will give an incentive for the regime to kill more innocent Syrian people," Haytham al-Mallah, an opposition figure, told broadcaster Al Arabiya.
The opposition Syrian Revolution General Commission accused the summit of "ignoring and abandoning" the rights of the Syrian people.
In Saudi Arabia, US Secretary of State Hillary Rodham Clinton held talks with King Abdullah on Friday to exert more pressure on al-Assad. Clinton is to head to Turkey to attend the second Friends of Syria conference on Sunday.