Jihadists kill 270 in Homs gas field raid

Syrian observers says 270 people have been killed since jihadists seized a gas field in Homs, while two women have been stoned to death.

Armed rebels from the Islamic Front, an umbrella of Islamist rebel groups in Syria, drive past buildings damaged during fighting between Syrian government forces and opposition forces on July 19, 2014 in Aleppo. (AFP)

Jihadists have killed 270 Syrian regime fighters, civilian security guards and staff since seizing a gas field in Homs province, most of whom were executed, a monitoring group says.

The Syrian Observatory for Human Rights also reported that a woman accused of adultery was stoned to death by the Islamic State (IS) in the northern city of Raqa, in the second such case in as many days.

The Observatory described Thursday's takeover of the Shaar field as "the biggest" anti-regime operation by the IS since the jihadist group rose to prominence last year among rebel groups in the Syrian conflict.

The watchdog said it had documented "the death of 270 people killed in the fighting or executed" since the takeover of the field in central Syria.

"A large majority of the men killed were executed at gunpoint after being taken prisoner following the takeover of the camp," Observatory director Rami Abdel Rahman said on Saturday.

"Eleven of the dead were civilian employees, while the rest were security guards and National Defence Forces members," he added.

On Saturday, regime forces, a day after launching a counter-attack, had "re-taken large areas of Shaar", according to Abdel Rahman. "Fighting is continuing around the gas field".

Gruesome footage apparently recorded by the jihadists at the gas field and distributed via YouTube showed dozens of bodies, some of them mutilated, strewn across a desert landscape.

On Friday night on a main square in Raqa, IS jihadists stoned to death a woman they accused of adultery, the Observatory said, citing residents of their stronghold.

"Because residents refused to take part in the stoning, the IS fighters themselves executed the woman," it said, adding that they pulled up a lorry filled with rocks for the killing.

The jihadists also stoned a young woman to death for adultery in Raqa on Thursday. Abdel Rahman identified her as a 26-year-old widow.

According to a local activist, who said that the public stoning took place in a square in the Raqa provincial town of Tabqa, residents are "terrified but do not dare react to such barbaric methods".

The IS, which proclaimed a "caliphate" straddling Syria and Iraq last month, has also taken over Syria's oil-rich Deir Ezzor province.