Syria's Kurds have imposed compulsory military service for their men to ward off a push by self-declared jihadists in the predominantly Kurdish areas in northern Syria, Kurdish officials said.

The move reflects fears among Syrian Kurds that the ongoing offensive by the Islamic State group in their region may potentially reverse gains made by their ethnic minority in the past three years.

Juan Mohammed, a spokesman for the Kurdish city of Qamishli, said on Thursday Jazira - the largest of the three Syrian Kurdish territories in size and population - adopted the draft law this week.

It requires all adult males serve in "self-defence" duty for six months.

The law was approved on Sunday by the legislative council that acts as Jazira's local parliament. It went into effect this week.

Territorial gains

The Kurds - a long ostracised community in Syria - have made unprecedented gains amid the three-year-old civil war, carving out a semi-autonomous territory in the north as overstretched government troops abandoned the region to focus on defending Damascus, President Bashar Assad's seat of power.

In November, the Syrian Kurds declared their own civil administration in areas under their control, dividing it into the regions of Afrin, Kobani and Jazira.

Kurdish fighters of the People's Protection Units successfully pushed out other rebel groups from a string of towns and captured stretches of territory along the borders with Turkey and Iraq.

But things changed this month, after fighters from the Islamic State seized territories straddling the Iraq-Syria border where they declared a self-styled caliphate.

Using advanced weapons seized from Iraqi forces, the Islamic fighters launched an offensive against the Syria's northern Kurdish region of Kobani, also known as Ayn Arab, capturing several predominantly Kurdish villages.

The fighting between the Syrian Kurds and the Islamic State, which broke out on July 2, left dozens dead on both sides, according to activists. Hundreds of Kurds have flocked from neighboring Turkey to help their brethren, the activists said.

"The Islamic State is reinforcing its positions around us and there are clashes,'' said Kobani-based Kurdish journalist Barzan Isso.

Isso told the Associated Press news agency that according to the draft law, every family was required to have one of its male members between the ages of 18 and 30 do the service. After six months, the men can decide if they want to go to the front lines.

Kurds are the largest ethnic minority in Syria, making up more than 10 percent of the country's 23 million people. The Kurdish civil administration is dominated by the Kurdish Democratic Union Party, or PYD, Syria's most powerful Kurdish group.

Source: Agencies