BEIRUT/ISTANBUL (Reuters) - Turkey-backed Syrian rebels began an attack on Islamic State’s symbolically potent stronghold of Dabiq in northwestern Syria on Saturday, a rebel commander said, taking territory that has all but cut it off according to a war monitor.

Turkey’s President Tayyip Erdogan on Saturday said the rebels were advancing on Dabiq and a Turkish security source said they had that morning cleared the militants from the hamlet of al-Ghaylaniyeh.

The Syrian Observatory for Human Rights, a Britain-based war monitor, said the rebels had also taken the villages of Irshaf and Ghaitun, which would all but cut off Dabiq and another large village, Soran, in an isolated pocket surrounded by insurgents.

Dabiq is symbolically important to the jihadist group because it is the site of an apocalyptic Islamic prophesy, and Islamic State has stationed around 1,200 of its fighters there said the Observatory, a Britain-based war monitor.

Euphrates Shield, the campaign by Turkey and allied Syrian rebels to clear Islamic State from areas along the border between the two countries began in August.

A rebel commander in the Euphrates Shield operation said the attack on Dabiq had started on Saturday morning and the Observatory said the rebels backed by Turkish tanks and warplanes had begun their attack on the village’s environs.

However, the Turkish military sources said the operation was ongoing.

“The operation for Dabiq started 10 days ago. We started the effort to take control of the region from the south. Daesh (Islamic States) targets are being hit by Turkish fighter jets and artillery” one of them said.

According to Islamic tradition, Dabiq will be the site of a final battle between Muslims and infidels heralding Doomsday, a prophesy that the jihadist group had encouraged its supporters to regard as imminent and named one of its publications “Dabiq”.

However, in a recent edition of its al-Naba online publication, Islamic State appeared to step back from that position, saying that the coming battle for Dabiq between it and the Turkey-backed rebels was not the one in the prophesy.

While Euphrates Shield has pushed Islamic State from its last foothold on Syria’s Turkish border, a longer campaign by the U.S.-backed, Kurd-dominated Syrian Democratic Forces has recaptured swathes of territory from the group since last year.

Islamic State also faces an expected assault on Iraq’s Mosul, the largest and most important city it has held since its lightning advance across huge tracts of Syria and Iraq in summer 2014.