Regime forces reportedly seize the last main road connecting al-Bab with Raqqa, Daesh's de facto capital in Syria.
Daesh is "completely besieged" in al-Bab after forces loyal to Syria's regime cut off a road into the group's last major stronghold in the country's Aleppo province, a war monitor said on Monday.
The regime advances came after its announcement on Thursday that it was expanding operations against Daesh in the country's north. Its gains draw the regime closer to potential conflict with Turkish-backed Syrian opposition forces, who are also making inroads against Daesh in the region.
"Al-Bab is now completely besieged by the regime from the south, and the Turkish forces and rebels from the east, north and west," said the UK-based Syrian Observatory for Human Rights.
"The regime's forces and allied militia seized the only and last main road used by Daesh between al-Bab and Raqqa," Observatory chief Rami Abdel Rahman told Agence France-Presse, referring to Daesh's de facto capital in Syria.
TRT World's lolo ap Dafydd reporting from the Turkish border city of Gaziantep said that if al-Bab falls, it will open up "the routes further south towards Raqqa."
Meanwhile, experts from Turkey, Russia Iran and the UN on Monday started a technical meeting in Kazakhstan's capital, Astana, to discuss in detail the implementation of the Syrian ceasefire agreement brokered in December by Turkey and Russia, Kazakhstan's Foreign Ministry said.
Jordan was also expected to take part for the first time in the Astana meeting, the foreign ministry spokesman said.
He said the meeting would review the implementation of the cessation of hostilities, discuss a proposal from the Syrian opposition about the ceasefire, and determine options about how to implement it.
A 14-member Russian delegation, including lawmakers, is scheduled to visit Syria's capital Damascus on Monday, and is expected to meet regime leader Bashar al Assad, according to Russian news agency Sputnik.