Two British special forces soldiers have been seriously injured in an Islamic State missile attack in Syria.
One Kurdish fighter was reportedly killed, happened on Saturday morning, news report.
The soldiers are thought to have been airlifted from the scene by US forces for medical treatment.
British and US special forces are working alongside Kurdish troops against IS in northern Syria.
Rudaw news, a Kurdish outlet, reports that the attack was on a Syrian Democratic Forces (SDF) base in Deir al-Zour.
An SDF official told Rudaw: “Due to a smart missile attack by ISIS, a fighter of the YPG was killed and another wounded, in addition to two British soldiers.”
A Ministry of Defence spokesman said: “We do not comment on special forces.”
The attack comes after Donald Trump tweeted on 19 December that “we have defeated ISIS in Syria, my only reason for being there during the Trump Presidency”.
Just this week the president was contradicted by Foreign Secretary Jeremy Hunt, who said IS was not defeated by “a long way”.
US president Donald Trump said in December that he was withdrawing US troops from Syria, where he claimed Isis had been defeated.
Mr Trump said: “We have defeated Isis in Syria, my only reason for being there during the Trump Presidency.”
The move shocked US allies and American defence officials alike, with US defence secretary Jim Mattis and a top US official in the fight against IS, Brett McGurk, resigning soon after. Analysts and military experts, who disagree with Mr Trump, have said the threat posed by Isis still remains.
British special forces are the only military personnel understood to be operating in Syria alongside the US.