Bus bomb in Syria's Afrin kills three, wounds 20

A bomb planted on a public bus in the northwest Syrian town of Afrin killed three civilians and wounded about 20, several witnesses told Reuters on Sunday.

The blast came on the first anniversary of Operation Olive Branch, an air and ground assault by Turkey on the mainly Kurdish Afrin to drive out the Syrian Kurdish YPG militia.

Protests were held in some regional centres in protest at the Turkish-backed seizure of Afrin, AFP said.

Turkish President Tayyip Erdogan said it and similar attacks "will never discourage our fight in Afrin".

"This process will continue without hesitation in Afrin, in Jarablus or in al-Bab," he said, mentioning two other towns under the control of Turkish-backed forces. His comments came during a phone call with Defence Minister Hulusi Akar, state-owned Anadolu Agency reported.

No group has claimed responsibility for Sunday's attack.

It follows a blast on Wednesday in Manbij, a northern Syrian town controlled by a militia allied with US-backed Kurdish forces, claimed by the Islamic State (IS) group, which killed two US troops and two civilians working for the US military.

Ankara considers the YPG an extension of the outlawed Kurdistan Workers Party (PKK) that has waged an insurgency on Turkish soil since 1984.

Erdogan said last month that his army would launch an operation against the YPG east of the Euphrates. US President Donald Trump later announced he would pull all US forces out of Syria, alarming allied Kurdish leaders who run much of the north.

The Kurdish-led Syrian Democratic Forces (SDF), an umbrella group dominated by the YPG and Washington's main Syrian partner in the fight against IS, controls territory in northeast and eastern Syria, which makes up about a quarter of the country.

The US decision to leave Syria has led the Kurdish leaders to urge Russia and its ally Damascus to send forces to shield the border from the threat of the Turkish offensive.

Residents in the Kurdish-controlled city of Qamishli protested Sunday to mark the anniversary of the Turkish offensive on Afrin, Reuters reported.

Thousands took to the streets holding photos of fallen Kurdish fighters and banners that read "no to Turkish occupation" and "it's time to free Afrin". 

The YPG in a statement pledged to continue its "struggle" to retake Afrin from Turkey's "occupation".