Al-Qaeda linked Syrian rebels have been accused of seizing 43 UN soldiers in the Israeli-occupied Golan Heights and trapped another 81 in the region, the UN has said.

The US said on Thursday it believed members of the Nusra Front were among those who captured 43 Fijian soldiers serving in the UN disengagement observer force near Quneitra, a crossing from Syria into Israeli-occupied territory.

A further 81 soldiers from the Philippines are understood to be under siege near Rwihinah. The Philippine government said its troops refused to give up their weapons when confronted.

The capture and standoff come after Syrian rebels, including Nusra Front fighters, stormed the Quneitra crossing on

Wednesday, sparking an exchange of fire with Israeli troops.

In a statement, the US said it condemned the action by rebels groups "including the UN Security Council-designated terrorist group, the Nusra Front", which is al-Qaeda's primary affiliate in Syria.

The UN Security Council said it held responsible "terrorist groups and by members of non-state armed groups".

The Golan Heights is a strategic plateau captured by Israel in a 1967 Middle East war.

Syria and Israel technically remain at war. Syrian troops are not allowed in an "area of separation: under a 1973 ceasefire formalised in 1974.

The UN force monitors the area of separation, a narrow strip of land running about 70km from Mount Hermon on the Lebanese border to the Yarmouk River frontier with Jordan.

It comprises 1,223 soldiers from Fiji, India, Ireland, Nepal, Netherlands and the Philippines.

Austria, Japan and Croatia have all pulled their troops out of the monitoring force due to the deteriorating security situation and spillover from the Syrian war.

UN officials noted that troops monitoring the area have been abducted twice in the last year, but released safely.