Extremists and allied fighters withdrew from a key area of north-western Syria Tuesday (August 20th) as President Bashar al-Assad's forces pressed an offensive against the extremist-run Idlib region, AFP reported.

The town of Khan Sheikhun on the region's southern edge has been a key goal for the government as it lies on the main highway through Idlib province connecting the capital Damascus with second city Aleppo.

In recent weeks, regime forces have inched forward towards the Idlib region, nibbling away at the southern edges of the bastion.

In the early hours of Tuesday, anti-Assad fighters pulled back from Khan Sheikhun and the countryside to its south, the Syrian Observatory for Human Rights said.

The withdrawal means an important Turkish observation point in the nearby town of Morek as well as a string of surrounding villages are effectively surrounded by government forces, Observatory chief Rami Abdel Rahman said.

All roads leading out of the area are either controlled by government forces or within range of their guns, he said.

A Tahrir al-Sham spokesman denied its forces had withdrawn from the countryside around Morek, adding they had regrouped in the south of Khan Sheikhun after heavy bombardment.