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
Theresa May will make her pitch to lead the Conservative party today, 90 minutes before long-time favourite Boris Johnson.
Cool temperatures and breezy conditions with a top temperature of 20 Celsius (68 F).
Suicide bombers targetting Istanbul's airport incited panic to take lethal advantage in an attack that echoed the Brussels airport atrocity.