Iran on Sunday welcomed the proposed ceasefire in Syria brokered by Russia and the United States, but said a monitoring system was needed to stop it being exploited by "terrorists".

"Iran welcomes any establishment of a ceasefire in Syria," foreign ministry spokesman Bahram Ghasemi said. 

"The continuation and sustainability of a ceasefire relies on the creation of a comprehensive monitoring mechanism, in particular control of borders in order to stop the dispatch of fresh terrorists, as well as weapons and financial resources for the terrorists."