Syria's moderate opposition said on Wednesday that they will respect the recently reached ceasefire 'for two weeks' in a statement released.

"The High Negotiations Committee believes a provisional truce for two weeks would provide a chance to determine the commitment of the other side" to the ceasefire, the group said in a statement.

The opposition group said on Feb. 22 it accepted a ceasefire deal announced by the United States and Russia if humanitarian "conditions" were met.

The statement by the Riyadh-based High Negotiations Committee came hours after Moscow and Washington said a ceasefire in war-torn Syria was set to begin overnight Friday-Saturday.

"After HNC general coordinator Riad Hijab presented the results of his discussions with opposition factions across all fronts, we agreed to respond positively to international efforts to reach a truce deal," the HNC said.

But its "commitment to the truce is conditional" on the lifting of sieges, release of prisoners, a halt to bombardment of civilians and the delivery of humanitarian aid.

The statement said the ceasefire "should be announced simultaneously by all sides".

The United States and Russia announced plans on Feb. 22 for a cessation of hostilities in Syria, excluding Daesh and Nusra Front militants, that would take effect starting on Saturday.