Russian-backed regime forces seized a cluster of towns and villages in northwest Syria Thursday, as deadly air strikes hit the opposition-held bastion, a monitor said.
Seven civilians died in air strikes in the south of the bastion, the Syrian Observatory for Human Rights said, a day after regime air strikes killed 12 others, including six children in a single town.
Bashar al-Assad's forces have been chipping away at the southern edge of the stronghold for three weeks, after months of deadly bombardment.
Last week, the regime took control of the town of Khan Sheikhoun on a key highway that runs through Idlib province, linking Damascus to second city Aleppo.
Overnight, pro-regime fighters "managed to advance in the southern Idlib countryside", according to the head of the Britain-based Observatory, Rami Abdel Rahman.
They took control of the towns of Al-Tamaanah and Al-Khuwayn, as well as nearby villages, east of Khan Sheikhoun, he said.
"The forces are trying to further extend their control in the area of Khan Sheikhoun before they advance north in the direction of the town of Maaret al-Noman," he added.
Maaret al-Noman is the next stop northwards on the Damascus-Aleppo highway.
Regime air strikes killed 12 civilians -- half of them children -- in Maaret al-Noman on Wednesday.
Also on Wednesday, another four civilians, including one child, were killed in other parts of the bastion.