At least 25 people were killed in northwestern Syria in air strikes carried out by the Syrian government and Russia, the Syrian opposition-run rescue service known as the White Helmets said early on Monday.

Russian and Syrian jets struck the rebel-held city of Idlib in northern Syria on Sunday, military sources said, as President Bashar al-Assad vowed to crush insurgents who had swept into the city of Aleppo.

The army also said it had recaptured several towns that rebels had overrun in recent days.

Residents said one attack hit a crowded residential area in the centre of Idlib, the largest city in a rebel enclave near the Turkish border where around four million people live in makeshift tents and dwellings.

At least seven people were killed and dozens injured, according to rescuers at the scene. The Syrian army and its ally Russia say they target the hideouts of insurgent groups and deny attacking civilians.

Ten children were among the dead in the air strikes in and around Idlib and other targets in rebel-held territory near Aleppo on Sunday, according to the White Helmets.

The total death toll from Syrian and Russian strikes since Nov. 27 had climbed to 56, including 20 children, the group added in a statement on X.

Reuters could not independently confirm the battlefield accounts.

The insurgents are a coalition of Turkey-backed mainstream secular armed groups along with Hayat Tahrir al-Sham, an Islamist group that has been designated a terrorist outfit by the U.S., Russia, Turkey and other states.

In a joint statement, the United States, France, Germany, and Britain urged “de-escalation by all parties and the protection of civilians and infrastructure to prevent further displacement and disruption of humanitarian access”.

The insurgents seized control of all of Idlib province in recent days, the boldest rebel assault for years in a civil war where front lines had largely been frozen since 2020. (Reuters)