Israeli tourists are flocking to the Golan Heights to catch a glimpse of the black banners of jihad, with al-Qaida linked fighters now in control of swathes of the demilitarized zone on the Israeli/Syrian border.

Rebels groups including the jihadist group Jabhat al Nusra (al-Nusra Front) have pushed Syrian government forces from the area, which for years was an internationally monitored buffer zone between the Syrian and Israeli military after the 1973 conflict between the countries.

Visitors have been attempting to catch glimpses of the feared militants across the border from viewing points on the heights, reports Vocativ, where smoke can be seen rising from villages where combat rages, and militants spotted in jeeps emblazoned with jihadist insignia.

One Israeli commanders said that the border was now more unstable than any time in the last 40 years.

"Who is in control over there? We don't know," Colonel Nir Ben David, a senior officer with the Northern Command of the Israeli Defense Forces, told the Washington Post, pointing at Syrian villages across the border.

Nusra fighters recently besieged a United Nations base in the area after sweeping into the border region, and in a separate incident took 45 Fijian peacekeepers hostage, driving UN forces out of the area. All were subsequently released. UN forces have now abandoned the demilitarized zone.

As rebels battle forces loyal to president Bashar al Assad from the region, violence has spilled across the border.

Mortars and tank shells have struck kibbutz settlements near the border, and on Tuesday a Syrian air force jet was shot down after it strayed into Israeli air space.

On the Israeli side of the border are many Druze, a Muslim minority sect loyal to president Assad, which al-Nusra regards as heretical.

They fear for the safety of relatives and members of the community across the border should rebels regain complete control of the border region.

Experts said that it was a matter of time before jihadist groups in Syria started deliberately targeting Israel.

"I think it is only a matter of time before they turn to Israel, a year, half a year. All other radical groups in the region — in the Sinai, in Lebanon — at some point they stop fighting their local enemies and start carrying out attacks against Israel," Eyal Zisser, an expert on Syrian affairs at Tel Aviv University told the Post.