BEIRUT (Reuters) - Air strikes have killed more than two dozen civilians in northwestern Syria in the last two days in an escalation of a Russian-backed offensive against the last major rebel stronghold, a war monitor and local activists said on Saturday.

FILE PHOTO: A man rides on a motorbike past rubble of damaged buildings in the city of Idlib, Syria May 24, 2019. REUTERS/Khalil Ashawi

An air strike in the village of Deir Sharki killed seven members of one family, most of them children, on Saturday, the Syrian Observatory for Human Rights said. Another seven people were killed by bombardments in other areas, it said.

On Friday, air strikes in the village of al-Haas killed 13 people. The dead included a pregnant woman and her unborn baby, local activists and the Observatory said. They had been seeking shelter after fleeing another area.

The bombardment forced a wave of people to flee northwards from the targeted areas, the Observatory and local activists said.

“They are bombing the towns and their outskirts to push people to flee,” Observatory Director Rami Abdulrahman said, adding that hundreds of families had been uprooted from areas that had so far largely been spared in the almost four-month offensive.

The Syrian state news agency SANA said the army was continuing operations against “the terrorist organisations in rural Idlib” and had widened its area of control around the rebel-held town of Khan Sheikhoun, currently a focal point of the offensive.

Russia and Syria have said their forces are not targeting civilians but militants including the Nusra Front, a jihadist group known today as Hayat Tahrir al-Sham.

FIERCE CLASHES

Ahmad al-Dbis, safety and security manager for the U.S.-based Union of Medical Care and Relief Organizations (UOSSM), which supports medical facilities in the northwest, said the bombardment had widened into populated areas where there were no military positions.

“They are being targeted to drive the people towards forced displacement,” he told Reuters.

Dbis said the number of civilians killed by government or Russian forces stood at more than 730 since late April. The U.N. Office for the Coordination of Humanitarian Affairs has said more than 500 civilians have died in hostilities.

The northwestern region including Idlib province is part of the last major foothold of the opposition to President Bashar al-Assad.

The government advance towards Khan Sheikhoun threatens to encircle the last remaining pocket of rebel-held territory in neighbouring Hama province.

Captain Naji Musafa, spokesman for the rebel National Liberation Front, said fierce clashes were raging in the southern part of Idlib province and adjoining areas of Hama province.

France called on Friday for an immediate end to the fighting and in particular condemned air strikes on camps for the displaced.

The upsurge in violence has already forced hundreds of thousands of people to flee towards the border with Turkey, which backs some of the rebels in the northwest and has its own troops on the ground in the area.

The National Army, a Turkish-backed Syrian rebel force based north of the city of Aleppo, said technical problems had prevented it sending reinforcements to help the Idlib rebels, as it had promised on Friday.