JERUSALEM -- Syrian rebels on Wednesday took 20 United Nations peacekeepers hostage in the Golan Heights, demanding that the U.N. and the United States do more to force Syrian President Bashar Assad to withdraw his troops from a village in the area in return for the hostages’ release.

“If no withdrawal is made within 24 hours we will treat them as prisoners,” a video posted online by a group that identified itself as the Martyrs of Yarmouk said. The video showed U.N vehicles and an armored patrol car. At least two U.N. officials wearing blue helmets and flak jackets could be seen in the background.

It was the second incident this week in which rebel forces deliberately sought to internationalize their fight to topple Assad. On Monday, gunmen believed to be either members of the rebel Nusra Front or the related group al Qaida in Iraq attacked an Iraqi military convoy deep inside Iraq as it was escorting a group of unarmed Syrian civilians and soldiers.

As many as 50 Syrians and a dozen Iraqi soldiers were killed in the attack, which Iraqi Foreign Minister Hoshyar Zebari on Tuesday called a massacre.

Wednesday’s hostage taking involved 20 Filipino soldiers who were part of a U.N. observer force that patrols the no-man’s land between Syria and Israel in the Golan Heights, which Israel occupied in 1967.

“The U.N. observers were on a regular supply mission and were stopped near Observation Post 58, which had sustained damage and was evacuated this past weekend following heavy combat in close proximity,” the U.N. said in a statement.

In the video, the rebels said they would hold the U.N. workers until the Syrian army withdrew from the village of Jamiah, just a mile away from the Syria-Israel border.

The rebels accused the U.N. of collaborating with Assad’s forces.

More then 1,000 U.N. peacekeepers patrol the narrow corridor between Israel and Syria. Earlier this month, Croatia withdrew its troops from the force, expressing concern that they might be targeted after news coverage linked Croatia to a weapons shipment bound for the rebels.

Israeli officials have in recent weeks said they were worried that rebel groups operating in southern Lebanon might stage cross-border attacks into Israel.

“Of the rebel groups fighting in Syria, we have, at least in the last three to four months, seen more of the type of groups we would characterize as hard line,” an Israeli official told reporters in a briefing last month. “These are groups that concern us because they would possibly not have a problem attacking Israel or its allies in the future.”

Under the conditions of the briefing, the official could not be further identified.

Earlier this week, Israel’s ambassador to the United Nations, Ron Prosor, warned that the situation along the border with Syria was becoming increasingly hostile.

“So far, Israel has shown maximum restraint,” Prosor wrote U.N. Secretary-General Ban Ki-moon. “You must act as soon as possible before the situation deteriorates. . . . Israel will not stand by while its citizens’ lives are at risk from reckless behavior in Syria.”

Militant Islamist groups, particularly the Nusra Front, which the United States said in December is an alias for al Qaida in Iraq, have assumed an increasingly prominent role in recent rebel military advances.

Little is known about the Martyrs of Yarmouk group, but the name recalls a predominantly Palestinian neighborhood in Damascus that has been the scene of fierce fighting. Residents of Yarmouk have told McClatchy that Nusra was leading the anti-Assad forces in that combat.