Iraqi Kurdistan's leader threatened on Saturday to intervene to protect Kurds in neighbouring Syria, who are caught up in fighting between Kurdish forces and jihadists.

Massud Barzani's remarks came as fighting raged in Syria, which has been racked by civil war for nearly two and a half years.

Syria's Kurds, marginalised by Damascus for decades, have walked a fine line since the conflict began, trying to avoid antagonising forces loyal to President Bashar al-Assad or rebels fighting to overthrow him.

But fierce fighting broke out in recent weeks between Kurdish forces and Al-Nusra Front, which is also fighting Assad, after Syrian Kurds expelled the jihadists from the town of Ras al-Ain on the border with Turkey.

Barzani, president of Iraq's autonomous Kurdish region, called for an investigation by Iraqi Kurdish political parties into reports of "terrorists" killing Syrian Kurds.

If "it appears that innocent Kurdish citizens and women and children are under threat of death and terrorism, the Iraqi Kurdistan region will... be prepared to defend" them, Barzani said in a statement.

Iraq's Kurds have a three-province autonomous region in the north with their own armed forces and security apparatus, which are widely regarded as better trained than the Iraqi army.

According to the United Nations, the region hosts more than 155,000 registered Syrian refugees, most of whom are Kurds.

Iraqi Kurdistan is to hold a conference this month bringing together Kurdish parties from Iraq, Syria, Iran and Turkey, the four countries where the largest Kurdish populations reside.

"We want a complete agreement and a just and peaceful solution for the Kurdish issue," Barzani told a preparatory meeting for the conference last month.

Kurds in Syria make up 10 percent of the population and are mostly concentrated in the north.

Kurdish areas of Syria have been run by local councils since Assad's forces withdrew from the areas in mid-2012.