Syrian government aircraft pounded opposition-held areas in the country's northwest on Sunday, killing at least 34 in one strike on a town near the Turkish border, activists said.

The air raid on Darkoush was the deadliest of dozens launched across Syria's Idlib province, where an opposition offensive has left government forces in the area reeling. President Bashar Assad's troops have been unable to wrest back any of the ground lost, despite talk of a counteroffensive.

The Syrian military has been relying heavily on its airpower to try to stanch the opposition campaign, which captured the provincial capital, Idlib city, last month and the strategic town of Jisr al-Shughour on Saturday.

The Britain-based Syrian Observatory for Human Rights and the Local Coordinating Committees activist collective both reported the air raids Sunday on Darkoush, which is located 1 mile from the Turkish frontier. They said 34 people were killed.

The Jisr al-Shughour activist coordinating committee's Facebook page also put the death toll at 34, and published a list of names.

It marked the second consecutive day of heavy strikes on the town. On Saturday, more than a dozen air strikes on Jisr al-Shughour and surrounding villages killed at least 27 people, including at least 20 fighters.

The offensive is being conducted by an array of anti-Assad groups, including the Al Qaeda-affiliated Nusra Front, the hard-line Ahrar al-Sham and even some smaller mainstream rebel factions.

With the insurgents now in control of Jisr al-Shughour, the main fighting front has moved some 3 miles south of the town, said Observatory director Rami Abdurrahman. Anti-Assad fighters have been attacking government positions in a sprawling agricultural plain south of Jisr al-Shughour.

Syria's state news agency said the army ambushed a "convoy of terrorists" along a road in the plain, known as Sahel al-Ghab, destroying six vehicles and killing those inside.

The fight for Jisr al-Shughour began Wednesday and activists said thousands of fighters took part in the offensive. With the fall of Jisr al-Shughour, the government is left with a presence in only a few towns and military bases in Idlib province.