The Syrian Observatory for Human Rights said the pair were part of the the international anti-jihadist coalition, led by the United States.

"The two British soldiers were transported by helicopter to receive medical care," the observatory's director Rami Abdel told AFP.

A Kurdish fighter from the Syrian Democratic Forces (SDF) died in the attack in the village of Al-Shaafa in Deir Ezzor province, one of the last pockets of territory still controlled by IS in the Euphrates River valley.

The SDF, a coalition dominated by Kurdish fighters, has spearheaded the fight against IS, supported by several Western countries including the United Kingdom.

The international alliance seized the key IS holdout of Hajin in December after months of fighting that has seen the jihadists launch vicious counter-attacks.

IS, which once controlled swathes of Syria and Iraq, has been pounded by multiple offensives.

Since September, more than 1,000 jihadists have been killed in the fighting compared with just under 600 SDF members while 15,000 people have fled Hajin, according to the Observatory.

Last month US president Donald Trump announced the withdrawal of around 2,000 soldiers from Syria, deployed to support the SDF, claiming IS had been defeated.

The Syrian war, which began in 2011, has caused more than 370,000 deaths and forced millions of people to flee their homes.