A leader of an Al-Qaeda affiliated rebel group in Syria has called for a ceasefire with another Al-Qaeda-inspired movement, after internecine clashes between various Islamist anti-government factions resulted in hundreds of deaths in less than a week.

"The foreigners and supporters will pay the price for losing this great jihadi fighting field. The Assad regime will revive itself after it was close to disappearing. The West and the Shiites will find a place to enter into this battle,” said a recorded message from Abu Mohammed Golani, the head of the Nusra Front, posted on the organization’s Twitter feed.

"This unfortunate situation has pushed us to launch an initiative to save the battlefields from being lost. This will be done by forming an independent legal counsel by all the rebel factions in addition to a ceasefire."

Internecine fighting broke out on Friday in the province of Aleppo, after the Islamic State in Iraq and the Levant (ISIL) killed a local doctor.

There had been previous resentment towards the group – staffed predominantly with non-Syrian fighters – for the harsh regime it has imposed on controlled areas in the country, since entering the war last year. ISIL is also engaged in conflict in Fallujah in neighboring Iraq, which it plans to unite with Syria to form a caliphate.

Nusra, which also shares a radical ideology but is composed mostly of local fighters, united with several other splinter groups to carry out reprisals against ISIL throughout the country.

The Syrian Observatory for Human Rights, a UK-based monitoring body, says that more than 270 rebel fighters have already perished in the clashes, with heavy casualties on both sides, though ISIL appears to have been pushed back.

ISIL does not appear to be set to leave the country, accusing its erstwhile allies of being "enemies of Allah who are fighting us via the media" in a message on its Facebook page.

The disunity among opposition forces, and the ever-increasing prominence of radicals, is particularly ominous in view of the Geneva Peace Talks coming up later this month, for which the opposition has previously failed to form a representative coalition.

It also bodes badly for a chance to secure more support from the West, which has increasingly baulked at supporting out-of-control rebel groups, even as it still insists that President Bashar Assad must be removed.

UN stops counting the dead

The United Nations Office of the High Commissioner for Human Rights, which intermittently published the death tolls from the conflict, which has lasted nearly three years, says it will no longer do so. The body, which has no officials on the ground, says it relied on data from six different non-governmental organizations in the country, but that recently the number of reliable sources has dwindled to between two and three.

"It was always a very difficult figure," Rupert Colville, a spokesman for the UN body, told the AP.

"It was always very close to the edge in terms of how much we could guarantee the source material was accurate. And it reached a point where we felt we could no longer cross that line. So for the time being, we're not updating those figures."

The last figures published in July claimed that over 100,000 people had died. The Syrian Observatory for Human Rights says the death toll has now surpassed 130,000.