Fighters detonate four vehicles and launch 250 shells into Fuaa and Kafraya, activists say.
A new temporary truce has begun between pro-government and opposition forces in four Syrian towns, a group that monitors the Syrian conflict has reported.
Sunday’s ceasefire began in the rebel-held towns of Zabadani and Madaya outside the capital, Damascus, and the regime-held Shia villages of Fouaa and Kafraya in the northwestern province of Idlib near the
Turkish border, the Syrian Observatory for Human Rights said.
Last month, two truces in the four towns did not hold. It is not clear how long the new truce will last or who brokered it.
The UK-based observatory said that hours before the start of the truce, a coalition of rebels led by al-Nusra Front seized parts of Fouaa after fierce fighting against pro-government militias backed by the Lebanese Shia Hezbollah movement.
At least 74 rebels and 40 pro-regime fighters have been killed in the area since rebel forces on Wednesday launched a large-scale attack on Fouaa and Kafraya, the last remaining regime strongholds in Idlib.
Most of the province has fallen in recent months to the rebels.
Zabadani and Madaya are among the rebels’ last strongholds near Syria’s border with Lebanon.
Syrian government troops and allied Hezbollah fighters have been besieging the two mountain towns since July.
The possibility that hardline Sunni rebels, who view Shia Muslims as heretics, would be able to overrun Fouaa and Kafraya appears to have persuaded the Syrian regime and Hezbollah to slow down their bid to recapture Zabadani and Madaya.
Trained rebel fighters
Meanwhile, the observatory reported that 75 rebel fighters trained by US, British and Turkish forces had entered Syria on Friday night and Saturday morning.
The fighters are thought to be part of a planned US-backed force aimed at fighting the Islamic State of Iraq and the Levant (ISIL) group.
The initial US programme, signed off by Congress a year ago, set aside $500m and aimed to train some 5,000 rebel fighters.
But the programme has suffered a series of setbacks, including reported defections by trainees unhappy at instructions that they should fight only ISIL and not government forces.
An initial group of 54 fighters came under attack by Nusra Front after entering Syria in late July, according to the Observatory.
On Wednesday, US Central Command chief General Lloyd Austin admitted that only four or five of the US-trained fighters were operating inside Syria.
– With additional reporting from AFP