Syrian troops accused over ceasefire
Kofi Annan, the United Nations envoy to the Arab League, says Syria has not fully complied with his peace plan.
He is now calling on the UN Security Council to demand that Syrian troops are moved away from protesting cities back to their barracks.
The call comes as activists accuse Syrian security forces of attacking civilians in several cities.
The opposition movement says the UN-backed ceasefire is being only partially observed, as heavy weapons and government troops remain deployed in cities.
"There is no evidence of a significant withdrawal," the Syrian National Council's spokeswoman Basma Kodmani told a news briefing in Geneva.
"The ceasefire is . . . only partially observed . . . To us it clear that ceasefire implied withdrawal of all heavy weaponry from cities, populated areas. This has not happened."
Mr Kodmani also said that three people had been killed in the towns of Idlib and Hama since the truce deadline expired on Thursday morning.
The ceasefire, which was set up by UN-Arab League envoy Kofi Annan, came into force at dawn.
Syria in turn accused "terrorists" of planting a roadside bomb that blew up in Aleppo, killing one officer and wounding at least 24 cadets and officers in an attempt to sabotage the UN-backed ceasefire, state media said.
The blast killed a lieutenant colonel and civilians were among the wounded.
There was no independent confirmation of the blast in Syria, where media access is severely restricted.
Just hours before the deadline expired, the military unleashed a lethal offensive against protest centres, killing 25 civilians including 10 in the rebel stronghold of Rastan, the Syrian Observatory for Human Rights said.
Mr Annan's plan calls for the withdrawal of forces from urban areas, a halt to fighting, a daily two-hour humanitarian truce, the release of arbitrarily detained people, freedom of movement for journalists and the right to demonstrate.
While Syria has told the Arab League it will comply with the ceasefire as long as opposition forces do the same, residents in some of the worst-hit cities are sceptical.