A ceasefire agreement has been reached in the central Syrian city of Homs, according to local activists and a Lebanese TV channel that supports president Bashar Assad's government.

The deal reportedly calls a truce between pro-Assad forces and rebels holed up in Homs' old quarters, said activist Beibars Tilawi and the Hezbollah-owned channel al-Manar.

Homs-based activist Mr Tilawi said that if it holds, hundreds of fighters will be allowed to leave Homs to head to rebel-controlled countryside north of the city.

The agreement could end the longest-running clashes between pro-government forces and rebels since the uprising against Assad's rule began in March 2013.

Earlier, 18 people, including 11 children, were killed in car bomb attacks in two Syrian villages, state-run television said.

Reports said the attacks took place in Jabreen and Humayri villages, which are under government control.

Rami Abdurrahman of the Britain-based Syrian Observatory for Human Rights said the group's activists counted at least 15 dead from the blasts.

There was no immediate claim of responsibility for the bombings, but al Qaida- affiliated rebels of the Nusra Front have claimed several car bombings in recent weeks.

Rights groups have condemned Assad's government and the rebels fighting to oust him for using weapons and attacks that overwhelmingly kill civilians.