Fighting appeared to stop across most areas of western Syria on Saturday after a landmark "cessation of hostilities" came into effect under a U.S.-Russian plan that warring sides in the five-year conflict have accepted.

The temporary halt in fighting marked the first time world powers have been able to negotiate a pause in Syria's civil war and the United Nations hopes it can lead to a new round of talks to end the conflict.

A monitoring group and the United Nations reported only isolated fire in western Syria after the temporary ceasefire began at midnight Friday.