Two car bombs struck Syrian regime targets in the strategic Qalamoun region near the Lebanese border Wednesday, a day after troops made advances in the area, a monitoring group said.

The attacks, claimed by the Islamic State of Iraq and the Levant (ISIL) and Al-Nusra Front, two Al-Qaeda-affiliated groups, came after rebels were driven out of nearby Qara village on Tuesday, said the Syrian Observatory for Human Rights.

Syrian loyalists backed by Lebanon's Hezbollah movement have launched a major assault on Qalamoun, a mountainous region straddling key supply routes between Damascus and Homs as well as rebel smuggling routes criss-crossing the Lebanon border.

The Observatory said Wednesday's car bombs, which targeted a regime checkpoint and intelligence building near the town of Nabek, 80 kilometres (50 miles) north of Damascus, caused "powerful explosions".

But the Britain-based group could not immediately say how many people were killed or wounded.

A Syrian security source told AFP there was just one explosion at a checkpoint at the entrance to Nabek.

"The soldiers at the checkpoint stopped a suspicious car and the driver, who was a suicide bomber wearing an explosive belt, tried to escape but was shot dead by soldiers," the source said.

"However, the vehicle exploded," the source added, saying there had been "victims."

Fighting, meanwhile, raged elsewhere in Qalamoun, particularly around the rebel bastion of Yabrud, which came under army shelling Wednesday, and Deir Attiya, a regime stronghold where clashes with rebels erupted for the first time.

The army had earlier said it was "hunting" jihadists across the region, while rebels vowed to return to Qara.

Some 120,000 people are estimated to have been killed in Syria's uprising, which began with peaceful protests against President Bashar al-Assad's regime in March 2011 but escalated into a full-blown insurgency when his troops launched a brutal crackdown.