Syria's main opposition grouping said it accepted a ceasefire deal announced by the United States and Russia on Monday if humanitarian "conditions" were met, AFP reports.

The Riyadh-based High Negotiations Committee said in a statement that it "agreed to respond positively to international efforts to reach a truce deal". 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.