A London-based violence monitoring group reports that Syrian forces and rebels have been struggling for control of the Syrian village of Jamla, close to where the UN peacekeepers were detained.
A statement on the group's website said:
The Syrian Observatory received a footage reporting that rebel fighters will not released [release the UN personnel] until regular forces withdraw from the area.
The Jamla village and its surrounding areas have witnessed violent clashes in the past couple of days.
Rebel fighters from several factions took hold of the Mortar division and several checkpoints in Jamla.
More top news
A 62-year-old woman has been found alive more than a week after she vanished while on a hiking trip.
The first African American actor to play the lead role in Les Misérables on Broadway has died, aged 21.
Crisis talks are to be held on the future of curry houses as cheap supermarket deals and immigration rules threaten the £4 billion industry.