Syrian regime refuses to withdraw troops

Syria's foreign ministry said it wants "written guarantees" from the opposition movements before withdrawing its troops from flashpoints across the country.

The statement comes two days before a UN-backed deadline for the violence in Syria to cease.

Peace envoy Kofi Annan had "not yet presented written guarantees on the acceptance by armed terrorist groups of a halt to all violence," it said.

Meanwhile, the US has asked Syria to abide by a ceasefire agreement that is due to take effect this week as activists report the army is intensifying attacks against opposition fighters

Saturday saw some of the deadliest violence yet.

As many as 160 people were killed under heavy bombardment in the provinces of Idlib and Aleppo, and in the Latamneh suburb of Hama city.

Foreign Ministry spokesman Jihad Makdessi said earlier statements that Damascus would pull its troops from cities and their suburbs by Tuesday "is a wrong explanation."

On Friday, the United States released satellite images that it said showed Syria has artillery poised to hit residential areas and has moved some forces from one town to another despite calls for a withdrawal.

Robert Ford, the US ambassador to Syria, posted the commercial satellite images on Facebook in what seemed an effort to pressure Syrian President Bashar al-Assad to pull back forces.

Bashar al-Assad, last week accepted a ceasefire agreement brokered by the UN-Arab League envoy Kofi Annan calling for government forces to withdraw from towns and villages by Tuesday, and for the government and opposition fighters to lay down their arms by 6am local time on Thursday. 

The truce is meant to pave the way for negotiations between the government and the opposition over Syria's political future.