Syrian rebels fighting forces loyal to President Bashar al-Assad's regime have taken over the only crossing along the Israel-Syria ceasefire line in the Golan Heights, army radio reported on Thursday, citing military officials.
"The IDF (Israel Defence Forces) confirms that Quneitra crossing has fallen to the rebels," Israeli army radio said, referring to a frontier post in the centre of the plateau.
The crossing is seen as strategically important because of its position in a demilitarised zone of the Golan Heights, most of which Israel seized from Syria in the 1967 Six-Day War.
The Syrian Observatory for Human Rights, a Britain-based group that has been monitoring Syria's two-year conflict, also said the rebels seized the Quneitra crossing after clashing with Syrian government troops.
Both the Observatory and the Israeli radio station said fierce fighting was still under way in the actual town of the same name, which lies close to the crossing.
Contacted by AFP, a military spokesman refused to comment on the report but confirmed a closed military zone had been declared in the area.
Israeli security sources said the development raised concerns over the future of the crossing as it had been taken over by rebels whose position vis-a-vis the Jewish state was unclear.
Over the past three months, at least 16 wounded Syrians have been transferred to Israel through the crossing for medical treatment, some of whom were reportedly regime forces.
Two Syrians crossed on Wednesday and another few on Thursday morning but it was not immediately clear how the takeover would affect such transfers.
Israeli security sources said the main issue was that it created a worrying uncertainty at the crossing.
"Until now, the Quneitra crossing was Israel's only point of contact with Syria," an Israeli security source told AFP, speaking on condition of anonymity.
"Today this place has been taken over by people who we don't know, whose purpose we don't know, and we don't know whether they are with us or against us," he said.
He also noted the headquarters of the UN Disengagement Force was located very close to the crossing. Since 1974, UNDOF forces have been charged with monitoring the ceasefire between Syria and Israel.
Israeli security sources confirmed there were exchanges of fire in the area of the crossing, but said it was not yet possible to say whether it had been taken over.
"The incident is ongoing so it's very hard to say who is in control there," one source told AFP.
He said the military had warned Israeli farmers not to approach the area and that an unspecified number of injured Syrians had been taken to a hospital in northern Israel for treatment.
It was unclear whether they were rebels, government troops or civilians caught in the fighting
A spokeswoman for Ziv hospital in the northern town of Safed was unable to confirm or deny the report, referring all enquiries to the Israeli military.
The Quneitra crossing is the only direct passage between Israel and Syria and used almost exclusively by Druze residents of the Israeli-occupied Golan Heights who are allowed to cross over to study, work or get married.
Israel seized a large section of the strategic plateau from Syria in the 1967 Six-Day War and annexed it in 1981, in a move never recognised by the international community.
Israel and Syria are still technically at a state of war.