US soldier, first ever, 'wounded in Syria fighting'

A US soldier deployed in Syria to assist rebel groups fighting the Islamic State group was wounded over the weekend, the Pentagon said on Tuesday.

US military spokesman Jeff Davis said the soldier was wounded by "indirect fire" - a term that typically refers to rocket or artillery fire - north of Raqqa, the de facto capital of IS.

He was "not on the front line," Davis said.

Davis said it is the first American casualty in Syria that he is aware of since US military advisory deployed there at the end of last year.

The White House authorised the deployment of a small detachment of Special Operations troops to Syria to help bolster local forces fighting against IS.

More US troops have been deployed to Syria in recent weeks, bringing the total number close to 500 soldiers. 

American soldiers are focusing on aiding the Syrian Democratic Forces (SDF), a coalition dominated by the Kurdish militia YPG.

However, US forces courted controversy last week when images appeared showing them wearing YPG insignia, drawing harsh criticism from Turkey, which sees the Kurdish militia as a terrorist group.

"The support they give to the YPG... I condemn it," said Turkish President Recep Tayyip Erdogan said on Saturday.

"Those who are our friends, who are with us in NATO... cannot, must not send their soldiers to Syria wearing YPG insignia."

Ankara accuses the YPG of being an extension of the Kurdistan Workers' Party (PKK), which has fought an insurgency against the Turkish state for over three decades.

Meanwhile, battles against IS are currently raging in northern Raqqa eight days after the start of an SDF offensive, with support from air strikes by a US-led international coalition.

Another US soldier was injured last weekend in northern Iraq near the city of Erbil, also by indirect fire, Davis said.