SYRIA (AFP) — Clashes between anti-government fighters and regime forces killed 51 combatants on both sides in the northwestern part of this country Tuesday, a war monitor said.

Russia-backed regime fighters have for weeks been chipping away at the edges of the jihadist-run stronghold of Idlib — a province that borders Turkey — after bombarding it for months.

But hardline rebels and jihadists on Tuesday attacked loyalist positions in the south of the bastion, the Britain-based Syrian Observatory for Human Rights said.

“Violent clashes east of the town of Khan Sheikhun broke out at dawn after jihadist and opposition groups attacked regime positions,” Observatory chief Rami Abdel Rahman said.

The attack was led by the Al-Qaeda-linked Hurras al-Deen group and another jihadist faction — Ansar al-Deen — he said.

The fighting has killed 23 regime forces and 20 opponents, including 13 jihadists, the Observatory said.