Damascus: Syrian Kurds urged the opposition on Saturday to halt a siege against them by rebels. The Kurdish National Council, a pro-opposition umbrella group of Syrian Kurdish parties, condemned what it said was an ongoing assault “against unarmed civilians” by jihadist insurgents on the northern town of Ras Al Ain.

It said the rebels, who came across the border from Turkey, were shelling the town indiscriminately, and called on the main opposition National Coalition and the Free Syrian Army to “pressure these militants to stop this criminal war which is detrimental to the Syrian revolution”.

The Syrian Observatory for Human Rights said 33 people had been killed over the past 48 hours in Ras Al Ain clashes that pitted the jihadist Al Nusra Front against Kurdish fighters.

Observatory head Rami Abdul Rahman told AFP that 28 rebels were killed in these clashes as well as five fighters from the Kurdish Democratic Union, the Syrian branch of the rebel Kurdistan Workers Party of Turkey.

A resident of Ras Al Ain told AFP both sides appeared to be preparing for a fierce battle, with Kurdish fighters building fortifications and digging trenches, and rebels bringing in reinforcements from across the border.

Turkey, which supports the revolt against Syrian President Bashar Al Assad, is home to a sizeable Kurdish minority whose demands for greater independence it has moved to suppress, notably in air strikes on Kurdish militant groups.

Activists say Turkey may be using jihadists in Syria to fight its own battle against the Kurds.