Turkish-backed Syrian rebels on Saturday pushed into the Islamic State stronghold town of al-Bab in northern Syria, as nearby Syrian government forces backed by Russia halted their advance at a contact line drawn to keep the rival forces apart.
Monitors said the rebel force — the mainstay in the Turkey-backed Euphrates Shield campaign — gained control of a hospital as it entered the western edges of the town as part of a multisided push to crush the IS militancy.
Witnesses reported fierce fighting at al-Bab, located 40 kilometers south of the Turkish border, but there were no immediate reports of casualties.
Separately, Russia's Foreign Ministry said Syrian government troops backed by Russian airstrikes had "liberated" the nearby town of Tadef, described in a ministry statement as Islamic State's "most reinforced position near the city of al-Bab."
Russia's Tass news agency, quoting the ministry, said the government offensive at Tadef had "destroyed 650 militants," two tanks, heavy weaponry and nearly 20 all-terrain vehicles. Neither Syria nor monitors had confirmed those claims by late Saturday.
Analysts describe northern Syria as one of the most complex battlefields in the multisided war, which erupted in 2011 and has since claimed nearly 400,000 lives.
With the Syrian army now just kilometers from al-Bab and the Turkish-backed rival rebel force pushing into the city, some analysts warn of the potential for fresh violence between the two sides that could allow IS fighters to flee the area largely unscathed.
"It's clear the regime is in a hurry to reach al-Bab," a senior rebel official in the Free Syrian Army told Reuters on Monday. But Mustafa Sejari also warned that his Turkish-backed fighters would not hesitate "to fight government forces if they got in the way" of the rebel offensive against IS.
IS extremists seized control of al-Bab in 2014 as part of a large offensive in northern Syria and neighboring Iraq aimed at establishing an Islamic caliphate.
Largely Sunni Turkey entered the fray last August, with the aim of clearing its border area of extremists and forcing the withdrawal of thousands of Iran-backed Shi'ite militia currently fighting on behalf of the Damascus government on the Turkish frontier.