Approximately 30 armed fighters stopped and detained the peacekeepers in the Golan Heights area, the UN Disengagement Observer Force said Wednesday.
The observers were said to be on a "regular supply mission" when they were stopped. There had recently been heavy fighting in the area between the Syrian opposition and government forces, the UN said.
YouTube videos purport to show Syrian opposition fighters with the seized convoy, Reuters reports.
The UN said it has dispatched a team to attempt a resolution, but released no further details of the incident.
Many in the international community have expressed concern as Syria's bloody civil war stretches into the border regions of Israel, Turkey, Iraq, Lebanon and Jordan.