BEIRUT (AFP, Reuters) - Islamic State in Iraq and Syria (ISIS) militants have withdrawn from the last territory they held in Aleppo province after the Syrian army retook the Ithriya-Rasafa road and areas east of Khanaser, the Syrian Observatory for Human Rights reported on Friday (June 30).

"IS withdrew from 17 towns and villages and is now effectively outside of Aleppo province after having a presence there for four years," said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights.

Regime forces had been advancing on a sliver of south-eastern Aleppo province around a key highway linking Hama province to the southwest and Raqa province further east. Abdel Rahman said regime forces seized control of the road late Thursday night, prompting the remaining IS fighters to flee. A Syrian military source in rural Aleppo confirmed the withdrawal.

"The military operation is ongoing and Daesh withdrew from the Aleppan countryside towards rural territory in Hama and Raqa," the source told AFP, using the Arabic acronym for ISIS. "The Syrian army is clearing out the last few metres," the source added.

A military media unit run by the army's ally Hezbollah said soldiers had captured the Ithriya-Rasafa road and besieged ISIS's positions east of Khanaser.

It did not say the extremist group had abandoned those positions.

Since early 2015, multi-front offensives against ISIS have eaten away at territory the group held in Aleppo province. US-backed Kurdish and allied Arab fighters ousted the extremists from Kobane on the Turkish border in 2015 and from the key city of Manbij last year.

Rebels backed by Turkey seized the town of Al-Bab in February, and Syrian government troops have steadily chipped away at ISIS towns in the south of the province.

In neighbouring Raqa province, a US-backed offensive is bearing down on the provincial capital of the same name, which has served as the extremists' de facto Syrian capital.