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.

An air strike in the village of Deir Sharki killed seven members of one family, most of them children, on Saturday morning, 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.

Rami Abdulrahman, director of the Observatory said the government’s aim was apparently to force civilians to flee from areas that had been relatively unscathed in the military escalation that began in late April.

“They are bombing the towns and their outskirts to push people to flee,” he said, adding that hundreds of families were moving northwards away from the targeted areas.