U.N. Disengagement Observer Force troops watch the Syrian side of the Golan Heights at Mount Bental in late August.

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U.N. peacekeepers withdrawing from Syrian-controlled Golan Heights

The withdrawal follows the capture of some peacekeepers by Syrian rebels

The peacekeepers were eventually released; others escaped a militant siege

U.N. peacekeepers have been in the region since 1974

CNN  — 

U.N. forces withdrew Monday from the Syrian-controlled side of the Golan Heights, the world body confirmed.

The U.N. statement cited the “exceptionally challenging environment” posed by armed rebel groups advancing on peacekeeping positions its observer force has held for close to four decades.

The confirmation comes hours after a journalist working for CNN saw dozens of peacekeeping vehicles crossing into territory controlled by Israel.

The withdrawal comes a little more than two weeks after Islamic militant fighters took some peacekeepers hostage and besieged others.

Al-Nusra Front freed 45 U.N. peacekeepers from Fiji in good condition last week, while forces from the Philippines escaped after exchanging fire with militant fighters, according to media reports.

The incidents occurred after Syrian rebel fighters took control of the only border crossing between Israel and Syria in the Syrian town of Quneitra in late August.

U.N. forces have been stationed in the Golan Heights since 1974 following negotiations between Israel and Syria to reduce tensions along their shared border after hostilities in 1973. Israel has occupied a portion of the territory since seizing it during its 1967 war with Egypt, Jordan and Syria.

The U.N. Disengagement Observer Force includes 1,250 troops from six countries. In addition to Fiji and the Philippines, India, Nepal, Ireland and the Netherlands have troops assigned to the force.

Austrian troops who had been taking part in the forces in 2013 pulled out after fighting in the Syrian-controlled Golan Heights between rebels and Syrian government forces.

Golan Heights: Making wine in the shadow of war

CNN’s Kareem Khadder and Ben Wedeman contributed to this report.