Damascus: The Islamic State of Iraq and the Levant (Isil), which has taken over large swathes of war-torn Syria in just a few months, was on Thursday engaged in fighting Kurds and members of a Sunni tribe.

The Syrian Observatory for Human Rights said the well-equipped Kurds, who started fighting Isil soon after it emerged in Syria in spring last year, had on Wednesday taken back several hills surrounding the city of Ain Al Arab (Kobane in Kurdish) in the north.

Isil has been trying to take over Ain Al Arab - Syria’s third Kurdish city - and incorporate it into the Islamic “caliphate” it proclaimed last month.

The fighting killed 14 members of the Kurdish People’s Protection Units (PYG) and 35 Isil members. Dozens of other fighters were wounded, said the Observatory.

The fighting comes two weeks after some 800 Kurdish fighters entered Ain Al Arab from neighbouring Turkey to fight Isil.

There are some 3.5 million Kurds in Syria, comprising some 15 per cent of the population. With the country swamped in a war that broke out three years ago, the Kurds are seeking autonomy in the areas where they are a majority.

Eastwards, Isil pounded regime positions in Hassakeh, as they tried to surround the city of 200,000 Kurds, Arabs, Armenians and other Christians.

In the eastern, oil-rich province of Deir Al Zor, most of which is under Isil control, members of the Shaitat Sunni tribe fought the Islamists, tweeting about an “uprising” against the radical group.

The fighting erupted after Isil detained three members of the tribe, “violating an agreement” between the two sides, it said.

According to the Observatory, the Shaitat tribe had promised Isil it would not oppose it, in exchange for Islamists not harassing or attacking its members.

The Sunni Shaitat tribe extends across three villages - Abu Hamam, Kashkiyeh and Ghranij.

On Thursday, a day after fighting broke out, Isil members raided the three villages, searching houses and kidnapping or “detaining” an unknown number of people, said the Observatory, adding that fighting was raging in the Shaitat villages.

Meanwhile, Isil set up new checkpoints in the Deir Al Zor countryside, but gunmen opened fire at one of the checkpoints.

At least five fighters were killed in the fighting, including a Belgian.

Also on Thursday, the Observatory reported that Isil had imposed a strict dress code for women in Deir Al Zor, forbidding them showing any part of their bodies.

“Women... are completely forbidden from showing their eyes,” said an Isil statement that the Observatory said was distributed in areas under Islamist control in Deir Al Zor province.

Women are also forbidden from wearing “open abayas (traditional black gowns) that reveal colourful clothes worn underneath”, it said, adding that women “must not wear high heels”.

It threatened an unspecified punishment for women who violated the dress code, while also banning the sale of cigarettes and narguileh (water pipe) products, as well as smoking in public.

On another front in Syria’s complex war, the number of people killed in army shelling on an opposition-held town northeast of Damascus on Wednesday rose to 17, according to the Observatory.