Syrian rebels seize 21 UN observers near the Golan Heights (VIDEO)

Syrian rebels have released a video announcing they have seized a convoy of United Nations observers near the Golan Heights, Reuters reported.

The UN confirmed that armed fighters had detained 21 peacekeepers on the border between Syria and Israel and said that it has sent a team to negotiate their release, Israeli newspaper Haaretz reported.

The UN Security Council demanded the immediate release of the peacekeepers, according to Agence France Presse. UN peacekeeping chief Herve Ladsous said negotiations were underway.

"The members of the Security Council strongly condemned the detention of a group of more than 20 peacekeepers … by armed elements of the Syrian opposition," said Russian UN Ambassador Vitaly Churkin, this month's president told reporters, according to Haaretz.

In the video, a young man who identifies himself as a member of the “Martyrs of Yarmouk” brigade says his group will hold the United Nations Disengagement Observer Force forces hostage until Syrian President Bashar al-Assad’s soldiers leave the village of Jamla, which is located a mile from the ceasefire line with the Israeli Golan, Reuters reported.

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"If no withdrawal is made within 24 hours we will treat them as prisoners," he said, according to Reuters.

The man, flanked by armed rebel fighters, stands in front of three white “UN”-marked vehicles. The camera pans to show at least five people wearing light blue UN helmets sitting inside the vehicles.

In a second video, the same spokesman accuses the UN, the Assad government and Europe of “collaborating with Israel,” the Times of Israel reported.

UN deputy spokesman Eduardo del Buey said the UN peacekeepers were on a supply mission when their convoy was stopped at an observation point. The point had been damaged and was evacuated following heavy fighting last weekend, he said, according to Al Jazeera.

GlobalPost senior correspondent Noga Tarnopolsky said:

My well-connected colleague Sal Emergui from El Mundo reports the rebels have given Assad an ulitmatum.

Syrian activists said the peacekeepers were from the Philippines, but the UN has not revealed their nationalities, Al Jazeera said.

Human Rights Watch told Reuters that it was investigating the same rebel group which claims to have seized the peacekeepers for allegedly executing captured Syrian soldiers earlier this week.

The news came as the UN refugee agency announced that 1 million Syrians have fled the civil war in their country. 

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Watch the video below: