(CNN) -

Officials are still trying to secure the release of dozens of U.N. peacekeepers from Fiji who were taken captive by al Qaeda-linked rebels from Syria.

The peacekeepers were captured Thursday in the Golan Heights, a day after rebels seized control of a border crossing between Syria and the Israeli-occupied territory.

Filipino peacekeepers, who also came under assault from the rebels, were all reported to be safe after slipping past the attackers.

The peacekeepers are part of the United Nations Disengagement Observer Force, which has overseen a buffer zone in the Golan Heights since 1974 to maintain a ceasefire between Israel and Syria. Fighting from Syria's civil war spilled over into the buffer zone last week.

Uncertain location

The Fijians' exact whereabouts remain unclear after they were forced from their position near the Syrian town of Quneitra by the rebels.

They have access to food, water and medical supplies and are all believed to be in good health, Brig. Gen. Mosese Tikoitoga, the commander of the Fijian military, said in a statement Monday.

But the United Nations said Sunday that "no additional information on their status or location has been established."

An Israeli military official, speaking on the condition of anonymity, told CNN last week that the peacekeepers were being held by members of the al Qaeda-linked al-Nusra Front, one of the groups fighting the regime of Syrian President Bashar al-Assad.

The United Nations said it was continuing to "actively seek their immediate and unconditional release."

There was conflicting information on the exact number of peacekeepers being held. The United Nations put the number at 44, but Fijian authorities said Monday there were 45. Al-Nusra released pictures online over the weekend that purported to show 45 peacekeepers and their U.N. identification cards.

Filipinos escape

Other U.N. peacekeeping positions in the buffer zone have also come under attack since the capture of the Fijians.

Rebel fighters advanced to surround two posts where Filipino peacekeepers were based and began to attack the positions on Saturday.

The U.N. troops at one position were moved to safety. But the other post returned fire after coming under attack from mortars and machine guns. The exchange of fire prevented the peacekeepers from safely pulling back, the United Nations said.

But the trapped peacekeepers then managed to escape early Sunday and get to Camp Ziuoani, which is on the Israeli side of the border, the official Philippines News Agency reported.

Top military officials in the Philippines praised the peacekeepers' defense of their positions and dramatic escape, according to local media.

'Peacekeepers, not combatants'

The U.N. force in the Golan Heights also includes troops from India, Ireland, Nepal and the Netherlands.

Fijian and U.N. officials have been calling for the immediate release of the captive peacekeepers.

"These men are peacekeepers, not combatants in the Syrian conflict, and there is no need for them to be detained," Fijian Prime Minister J. V. Bainimarama said Friday.

He said authorities were "doing everything possible to secure their safe return."

U.N. Secretary General Ban Ki-moon has strongly condemned the detention of the peacekeepers.

The Golan Heights border crossing made headlines earlier last week, when the al-Nusra Front handed over American journalist Peter Theo Curtis to U.N. peacekeepers on the Syrian side of the checkpoint.