Bomb blasts killed more than 100 people in the Syrian coastal cities of Jableh and Tartous on Monday, monitors said, in a government-controlled area that host Russian forces.

Islamic State claimed responsibility for the attacks in the Mediterranean cites that have up to now escaped the worst of the conflict, saying it was targeting supporters of President Bashar al-Assad.

Scores were wounded in at least five suicide attacks and two car bombs, the Syrian Observatory for Human Rights said, the first assaults of their kind in Tartous, where government ally Russia maintains a naval facility, and Jableh.

State media confirmed the attacks but gave a lower toll.

Fighting has increased in other parts of Syria in recent weeks as world powers struggle to revive a threadbare ceasefire in western Syria and after peace talks in Geneva this year broke down.

State media reported that a car bomb and two suicide bombers attacked a petrol station in Tartous. In Jableh, one of the four blasts hit near a hospital, state media and the Observatory reported.