Pro-Syrian government forces advanced in an ISIL pocket in south-west Syria on Sunday, despite a threat to hostages seized by the extremist group last week, a media unit run by Damascus ally Hezbollah reported.
ISIS kidnapped 36 Druze women and children in a co-ordinated attack on their village in Sweida last week, residents of the southern province said on Monday.
The mainly government-held area has a large number of Druze residents and had been insulated from the conflict raging in the rest of the country since 2011. But on Wednesday, a series of suicide blasts and shootings claimed by ISIS left more than 250 people dead in the provincial capital and nearby villages, most of them civilians.
After the attack, extremists also abducted several dozen women and children from one village, according to war monitor the Syrian Observatory for Human Rights and Sweida residents. The Observatory, based in the UK, said four women managed to escape but another two died.
That left 14 women and 16 children in ISIS captivity, said Observatory head Rami Abdel Rahman. Another 17 men were unaccounted for, but it was unclear whether they had also been kidnapped.
ISIS has not claimed the kidnappings and no details could be found on its propaganda channels.
Despite the risk to the women, Syrian state television broadcast footage from near the scene of the fighting in south-west Syria, showing military vehicles moving along a road.
ISIL retains only a small area of Deraa province near the frontier with the Israeli-occupied Golan Heights, after army advances last week forced it to retreat.
A Hezbollah media unit said the Syrian army had advanced towards the town of Al-Shajara.
A non-Syrian source close to Damascus said the army had paused its offensive early on Sunday, but that this was for logistical reasons rather than because of the hostages. The Observatory reported air strikes against ISIL positions east of Sweida.
An informal communications channel has been opened with the extremist group to try to release the hostages, the source said.
According to news outlet Sweida24, the civilians were kidnapped from the village of Al-Shabki in the eastern hinterlands of Sweida province.
Sweida24 and other online outlets published a video that appeared to show one of the hostages making demands of the Syrian government, purportedly on ISIS's behalf.
AFP could not independently verify its authenticity, but several Sweida residents confirmed that a woman in the footage was among those missing.
The hostages mainly hail from two large families in Al-Shabki, said reporter Nour Radwan, who heads Sweida24.
The remote village lies in the eastern edges of Sweida province and has suffered some of the deadliest violence from Wednesday's attacks, with more than 60 civilians killed in the town, he said.
"Most of its residents are farmers and don't have much more than hunting rifles in terms of weapons, so there was little resistance from Al-Shabki compared to other villages," he told AFP.
"When IS saw that, it kidnapped the first batch of people from their homes and took them east towards the Badiya, according to survivors."
The Badiya is Syria's vast desert, which stretches from the country's centre to its eastern border with Iraq and includes several isolated ISIL-held pockets.
ISIL has also reached out to the families of those abducted with pictures and videos.
The extremists are demanding the release by the Syrian government "of detained IS-linked people, whose numbers are now being negotiated", said Mr Radwan.
ISIS also wants a halt to a Syrian regime offensive on its positions, he said.
Religious leaders from the Druze community have since stepped in, Mr Radwan and another local source with knowledge of the talks told AFP.
"As of Sunday, the hostages were still being held in the Badiya. Negotiations are happening between Daesh and Druze sheikhs," said the source, using the Arabic acronym for ISIS.
The extremists have lost urban strongholds in Syria but still hold parts of the Badiya, including northeastern areas in Sweida and territory by the Iraqi border.
Backed by Russia, Syrian troops have been waging an assault on an ISIS-held pocket of Daraa for nearly two weeks.
Since its bloody rise to power in 2014, ISIS has carried out multiple mass abductions in Syria and Iraq, including minorities.
It kidnapped more than 220 Assyrian Christians in north-east Syria in 2015 and another 270 Christians from a central village the following year. Most of the hostages were released after negotiations.
Under the group's ultra-conservative interpretation of Islam, minorities are considered "infidels" but ISIS also politicises them as regime loyalists.