Blast targets pro-Turkey rebel fighters in Syria's Afrin

A car bomb targeting a pro-Turkey Syrian rebel post in the northern city of Afrin on Sunday killed at least eight people including four civilians, a British-based war monitor has said.

Dozens were wounded in the blast and the death toll could rise, the Syrian Observatory for Human Rights said.

"The car bomb exploded near a position of pro-Turkey fighters" in a market, killing four civilians and four fighters, Observatory chief Rami Abdel Rahman said.

Nobody has claimed responsibility for the bombing in the northern Syrian city, which was seized from Kurdish forces earlier this year.

The blast coincided with threats from Turkey's President Recep Tayyip Erdogan on Wednesday of a new offensive against the Kurdish People's Protection Units (YPG) in Syria.

The city of Afrin was captured in March this year from the YPG by Syrian rebels supported by Turkey.

Ankara accuses the YPG of being "terrorists", and being aligned to the Turkish-Kurdish militant outfit the Kurdistan Workers' Party (PKK).

The YPG is the backbone of a US-backed alliance fighting the Islamic State group in Syria, causing frictions with Washington, with fighters from the militia present in areas along the Turkish border to the east of Afrin.

Erdogan said Turkey was planning to launch a new offensive within the "next few days" against the YPG in northern Syria.

A day later, a Turkish soldier was killed in the Afrin region after coming under fire from the YPG, the Turkish defence ministry said.

US President Donald Trump agreed on Friday "more effective coordination" with his Turkish counterpart in the war-torn country.

American forces are present in an area along the Turkish border east of Afrin, as part of the US-led coalition fighting IS.

Erdogan has strongly criticised Washington's support for the YPG-led Syrian Democratic Forces fighting IS in their last holdout in the far east of the country.

Syria's war has killed at least 500,000 people and displaced have the population since war broke out in 2011 with the brutal repression of anti-government protests.