HASAKEH, Syria - A coalition fighting the Islamic State group in Syria has received US armoured vehicles for the first time and a promise of new American support, a coalition spokesman said Tuesday.

"American armoured vehicles have arrived for the Syrian Democratic Forces (SDF) for the first time. This happened after the new US administration came to power," spokesman Talal Sello told AFP.

He said the decision to supply the vehicles was taken by Trump's administration, rather than in a simple continuation of US support under  Obama. "Before we used to receive light weapons, ammunition... with these armoured vehicles we've entered a new phase in the (US) support. It's a sign," Sello added. The SDF has long been a key partner of the US-led coalition fighting IS in Syria and Iraq, and Washington has previously supplied the coalition of Kurdish and Arab fighters with light weaponry and has sent US and other Western special forces as "advisers".

The US-led coalition has also backed the force with heavy air strikes targeting IS fighters.

The alliance has caused tensions between Washington and ally Turkey, which considers the main component of the SDF - the Kurdish YPG force - to be a "terrorist" organisation.

The SDF has been battling since November 5 to oust the militants from the city of Raqa, the group's de facto capital in Syria.

Sello said the Trump administration had pledged extra support "particularly in the fight for Raqa".

In a two-month offensive, the SDF has taken large areas of northern Raqa province.

The alliance was formed in October 2015, after the YPG Kurdish militia had already scored a string of victories against IS in northern Syria with air support from the US-led coalition.

Trump has said his focus in Syria will be battling IS, and on Saturday signed an executive order giving the US military 30 days to devise a plan to "defeat" the militant group.

The order, which called for a "comprehensive strategy and plans for the defeat of ISIS", was seen as meaning more US forces and military hardware moving into Iraq and Syria.