Al-Nusra Front captures Syrian Golan Heights crossing

Syrian opposition fighters, including the Al-Qaeda affiliated Al-Nusra Front, have taken control of the Syrian crossing of the Israel-occupied Golan Heights.

"Al-Nusra Front and other rebel groups took the Quneitra crossing, and heavy fighting with the Syrian army is continuing in the surrounding area," said Rami Abdel Rahman, head of the Britain-based Syrian Observatory for Human Rights.

The capture is thought to be the result of a coordinated attack by the Al-Nusra Front - designated a terrorist organisation by the US, UK and Saudi Arabia - and Ahrar al-Sham, a leading member of the Saudi-supported Islamic Front.

Israeli army forces - whose posts lie around 200 metres from Syrian posts - fired upon two Syrian army positions, responding to six mortar shells hitting the Israel-controlled portion of the territory.

"In response to the errant fire from the internal fighting in Syria, which hit Israel earlier today and injured an IDF (Israel Defence Forces) officer, the IDF just targeted two Syrian army positions in the Syrian Golan Heights. Hits were confirmed," it said in a statement.

The army did not specify whether the rocket fire came from the pro-government Syrian army or from opposition forces.

The Golan Heights, occupied by Israel since the 1967 Six-Day War, has been increasingly unstable since the outbreak of fighting in Syria in 2011, with Israel occasionally responding when fighting spills over into the contested territory.

The Israeli military struck nine military sites in Syria after fire from across the Syrian border killed an Israeli teenager

The Philippines last week pulled its peacekeeping forces out of the UN-monitored Golan Heights, citing security concerns, particularly in light of the seizing of 25 peacekeepers last year.

In 2013, the Quneitra crossing was captured by Syrian rebel forces, before being recaptured by the Syrian army soon after.

The incident led to the withdrawal of Austrian peacekeeping forces from the territory.

Though Israel and Syria have officially been at war since 1967, the Golan Heights had remained relatively peaceful under the Syrian Civil War.

The capture of the crossing in the Golan Heights marks a significant victory for the Syrian rebels, which observers have remarked are increasingly dominated by Islamist groups.

Though Assad portrays himself as an anti-Zionist and supporter of the Palestinians, the rise of the Al-Nusra Front and the Islamic State have caused some commentators to suggest he might be preferable to an Al-Qaeda inspired government in Damascus.

Fighting in Syria has claimed as many 200,000 lives since pro-democracy demonstrations against the Assad government in 2011 turned to violence.

Israel has attempted to stay relatively uninvolved in the Syrian conflict, only taking unilateral action to strike targets it claims were weapon shipments destined for the Lebanese Shia militants Hezbollah.