Witnesses said that Wali, a leader of the youth movement in the revolt against the regime of President Bashar al-Assad, was shot twice in the head in Thursday's attack.

The Syrian Observatory for Human Rights said Wali was a leading figure in the Kurdish National Council and the Kurdish Revolutionary Youth Movement.

The killing took place in front of the local council office in Ras al-Ain, a town in Kurdish-majority Hasaka province, the watchdog and activists said.

Friends said Wali had received a number of death threats and gone into hiding, only emerging to attend local demonstrations.

Syria's Kurds have engaged cautiously with the uprising but have also kept the rebel Free Syrian Army at a distance, fueling suspicions among some of collusion with the regime.

Numerous activists and intellectuals have been targeted by the Assad regime since the start of the 18-month uprising, which was initially peaceful and steadily militarised after months of violent repression.

In August 2011, renowned cartoonist Ali Ferzat, whose satirical drawings had been highly critical of the Assad regime, was seized by security forces and pro-regime militiamen and badly beaten, his hands especially.

Independent Syrian film producer and activist Orwa Nayrabia went missing in late August after trying to travel to Cairo, and his fate remains unknown.

Activist Adnan Wehbeh, known for his anti-regime stance, was assassinated at his medical clinic in June near Damascus by a security man dressed as a civilian, a watchdog said.

And singer Ibrahim Qashush, famed for an anti-regime anthem and nicknamed "the mocking bird of the revolution," was found dead in July 2011 with his throat slit and vocal chords ripped out.