A bomb blast in a bus killed three civilians Sunday in the northern Syrian city of Afrin on the first anniversary of a Turkish attack on the Kurdish-majority region, a war monitor said.

 

Nine other people, including fighters, were wounded in the explosion, the head of the Britain-based Syrian Observatory for Human Rights, Rami Abdel Rahman, told AFP.

 

Turkish troops and allied rebel groups seized the Afrin region from Kurdish forces in March last year after a two-month air and ground offensive.

 

"The explosion is the result of a bomb that was placed in a bus in the centre of Afrin," Abdel Rahman said.

 

It was not immediately clear who was behind the blast, the second to rock Afrin since December 16 when a car bomb killed at least nine people, including five civilians, near a pro-Turkey rebel post in the city.

 

That explosion came after Turkish President Recep Tayyib Erdogan threatened to launch a new offensive against the Kurdish People's Protection Units (YPG) in Syria.

 

Turkey accuses the YPG of being "terrorists", but the Kurdish militia also forms the backbone of a U.S.-backed alliance fighting the Islamic State group in Syria.