The United Nations has confirmed that an armed group captured 43 UN peacekeepers on the Syrian side of the Golan Heights on today, but a Defence Forces spokesperson has confirmed all Irish personnel are safe and accounted for.

The UN said 81 further peacekeepers were "currently being restricted to their positions in the vicinity of Ar Ruwayhinah and Burayqah".

Israel closed off the area around Quneitra yesterday after an officer was wounded by stray fire as Syrian rebels, including fighters from the Al-Qaeda affiliate Al-Nusra front, stormed the crossing.

No details were released on the nationalities of the detained peacekeepers but six countries are contributing to the 1,200-strong unit: Fiji, India, Ireland, Nepal, Netherlands and the Philippines.

"Forty-three peacekeepers from the United Nations Disengagement Observer Force (UNDOF) were detained early this morning by an armed group in the vicinity of Quneitra," the UN said in a statement.

UN officials noted that the peacekeepers monitoring the armistice line between Israel and Syria were detained twice last year and released safely.

"The United Nations is making every effort to secure the release of the detained peacekeepers and to restore the full freedom of movement of the force throughout its area of operation," it added.

The UN secretary general, Ban Ki-moon, condemned the action calling for all of the detained to be released and for the restriction of movement put in place for UNDOF peacekeepers to be lifted. 

In June 2013, there was a similar takeover of the crossing by rebel forces, but the Syrian army managed to regain control.

On the Israeli-occupied side of the Golan, an AFP correspondent saw six white UN vehicles crossing the ceasefire line into Syrian territory through a gate in the fence 25km south of the Quneitra crossing.

Quneitra is the only crossing between the Syrian and the Israeli-controlled sides of the strategic plateau.

The Philippines, which has 331 troops serving in UNDOF, announced on Saturday that it will pull out of the peace force, citing security concerns.

Filippino defense officials said no fresh troops would be sent to serve in UNDOF once the current soldiers return from duty in October.

Last year the Philippines also considered pulling its Golan peacekeepers out after 25 of them were kidnapped but later freed by Syrian rebels in two separate incidents.

A Filipino soldier was also wounded by a wayward shell last year.

Since the Syrian conflict erupted in 2011, the plateau has been tense, with a growing number of rockets and mortar rounds hitting the Israeli side, mostly stray, prompting occasional armed responses.

During fighting yesterday, several mortars landed in or near UN positions, UN spokesman Stephane Dujarric said.

Israel, which has yet to sign a peace deal with Syria, seized 1,200 square kilometers of the Golan Heights during the 1967 Six-Day War and later annexed it in a move never recognised by the international community.

Meanwhile, Islamic State fighters have executed more than 160 Syrian soldiers captured during the IS storming of a key northern air base this week, a monitoring group has said.

The jihadists boasted on Twitter that they had killed 200 defeated troops and posted video of what they said was the garrison in headlong flight.

"IS executed more than 160 Syrian soldiers in three different places in Raqa province yesterday and at dawn today," said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights.

The soldiers were fleeing the jihadists' seizure of the Tabqa base on Sunday, which cemented IS control over Raqa province, capital of its self-declared Islamic "caliphate".

Abdel Rahman said the defeated garrison comprised 1,400 soldiers, 200 of whom were killed and 700 of whom managed to escape.

Of the other 500, dozens were captured last night as they attempted to cross the desert to government-held territory in the Orontes Valley to the west.

IS posted video footage showing young men in underwear being marched barefoot along a desert road. Militants shouted "Islamic State" and "There's no going back".

In Syria, the group controls all of Raqa province and much of Deir Ezzor further down the Euphrates Valley towards the Iraqi border.

It also controls most of the Sunni Arab heartland of neighbouring Iraq, north and west of Baghdad, including second city Mosul.

It has repeatedly posted often gruesome videos, both as a warning to those joining up to the Syrian army and as a propaganda tool to recruit volunteers from the wider Islamic world.