Daesh terrorist group no longer has a presence in Syria's Aleppo province after withdrawing from a series of villages where regime forces were advancing, a monitor said Friday.

"[Daesh] 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.

Assad regime forces had been advancing on a sliver of southeastern 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 Daesh 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.

"The Syrian army is clearing out the last few meters," the source added.

A second military source, quoted by Syrian state news agency SANA, also confirmed that Daesh had pulled out of territory along the Ithraya-Rasafa highway.

Since early 2015, multi-front offensives against Daesh have eaten away at territory the group held in Aleppo province.

U.S.-backed ground forces ousted the terrorists from Kobane on the Turkish border in 2015 and from the key city of Manbij last year.

Opposition forces backed by Turkey seized the town of Al-Bab in February, and Assad regime troops have steadily chipped away at Daesh towns in the south of the province.

In neighbouring Raqqa province, a U.S.-backed offensive is bearing down on the provincial capital of the same name, which has served as the terrorists' de facto Syrian capital.

Abdel Rahman described Friday's withdrawal as "a new loss for [Daesh] that decreases its influence and demonstrates that we are watching its collapse as an organisation that can manage geographical territory".

Syria has been in a state of intense conflict since war erupted in March 2011, after the Assad regime turned weapons against its own people.

Turkey-backed talks with participation of Russia and Iran aimed at reaching a lasting ceasefire will resume in the Kazakh capital Astana next week, before another round of U.N.-backed peace negotiations in Geneva in mid-July.