US-led airstrike killed 18 allied fighters in Syria after they were mistaken for Islamic State

An airstrike by the US-led coalition in Syria killed 18 members of allied rebel forces on the ground in Syria after they were mistaken for so-called Islamic State fighters, the Pentagon has announced.

A statement said the attack on Tuesday had incorrectly targeted members of the moderate Syrian Democratic Forces stationed to the south of the city Tabqa.

US Central Command indicated that it was the SDF themselves who had given the wrong co-ordinates for the strike, which was intended to target IS fighters nearby.

It was not clear which country had launched the missiles. A number of countries are taking part in targeted airstrikes led by the US.

The Syrian Democratic Forces are a multi-ethnic but predominantly Kurdish group which states its aims are to create a secular, democratic and federal state.

With the help of air and ground support from the US-led coalition, they have surrounded the IS-controlled city of Tabqa in central Syria.