US coalition denies attacking Shia forces on Iraq border

The US-led coalition in Syria has denied it carried out an attack on the Iraq border which killed dozens of Shia fighters and several of Iran's elite Revolutionary Guards.

A spokesman for the Iran-backed Kataib Sayyid al-Shuhada militia said 36 of its fighters had been killed in the attack on Monday and 75 others were wounded and receiving treatment.

"We hold the American army responsible for this act," the militia said in a statement late on Monday, noting that they were targeted with smart rockets.

Iraq's prime minister, Haider al-Abadi, said on Tuesday that an initial investigation showed that Islamic State launched the attack against the militia group.

"It seems that Daesh carried out a breach using artillery and car bombs," Abadi said in a televised press conference in Baghdad.

The US-led coalition, which is attacking Islamic State militants from the air in Syria and Iraq, said on Tuesday the allegations were "inaccurate" and denied conducting air attacks in that area at the time.

In a statement circulated by its supporters, Islamic State claimed it was responsible for the attack and said it had captured armoured vehicles, weapons and ammunition. Iraq's defence ministry declined to comment.

As Islamic State is driven back by an array of forces in Iraq and Syria, its opponents and their regional patrons are vying for control of territory and seeking to secure their interests in the wider region within a shrinking battlespace.

Monday's attack took place near Tanf in Syria, where US forces have twice before struck Iranian-backed militia in defence of a garrison used by US and US-backed forces.

Iran-backed Kataib Sayyid al-Shuhada is part of an umbrella of Iraqi Shia paramilitary groups known as the Popular Mobilisation Forces, which is answerable to Baghdad, but includes factions loyal to Iran's clerical leadership.

In an interview with Iran's Tasnim news agency, Abu Ala Welayi, Kataib Sayyid al-Shuhada's leader, accused the United States and Islamic State of jointly attacking his forces.

He said seven Revolutionary Guards had been killed, one of them being Hossein Qomi, their main commander and strategist.

No spokesman for the Revolutionary Guards was immediately available to comment.