United Nations-Arab League envoy Kofi Annan says Syria has agreed to a deadline of 10 April to begin implementing a six-point peace plan.
The plan calls for a UN-supervised ceasefire by all parties, withdrawal of soldiers and heavy weapons from cities and delivery of humanitarian aid.
Mr Annan has asked the Security Council for its backing for next Tuesday's deadline, with a full ceasefire within 48 hours.
Syria said last week it accepted the peace plan.
However, US Ambassador to the UN Susan Rice said Syria has made promises to the west before, but failed to keep to them.
Meanwhile, fighting in Syria is reported to be continuing in Idlib and Homs.
A network of anti-government groups said 65 people were killed on Monday. They included 40 in Homs, 14 in Idlib, six in Hama and five in Aleppo.