Iraqi security forces yesterday repelled an attack by Islamic State insurgents against an air base in Anbar province where US Marines are presently training Iraqi troops, Iraqi and US military officials said.

Militants from the jihadist group had attacked the Ain al-Asad base and the nearby town of al-Baghdadi on Thursday, leading to sporadic clashes in the town and in the surrounding areas overnight.

Later yesterday evening the Pentagon said in a preliminary report that the attack on Ain al-Asad air base was carried out by some 25 Islamic State fighters including several suicide bombers, some of whom evidently detonated their vests,

Rear Admiral John Kirby, the Pentagon press secretary, told reporters that most of the attackers, some of whom were in Iraqi uniforms, were killed by Iraqi security forces guarding the base.

The US officer added that no US troops were involved in the fighting and Iraqi forces suffered no casualties.

Coalition forces were several kilometres from the attack and at no stage were they under direct threat from this action

Al-Baghdadi has been besieged for months by Islamic State, which captured swathes of northern and western Iraq last year, prompting a campaign of US-led air strikes and the deployment of hundreds of US military advisers to the country.

A US defence official said the Iraqi forces had succeeded in stopping the attack and they had re-secured the facility.

“Coalition forces were several kilometres from the attack and at no stage were they under direct threat from this action,” the official said.

About 320 US Marines are training members of the Iraqi 7th Division at the base, which has been struck by mortar fire on at least one previous occasion since December.

Iraq’s Defence Ministry said on its website the Iraqi army killed eight assailants near the base, which is situated about 85 kilometres northwest of Ramadi.

Prime Minister Haider al-Abadi, a moderate Shi’ite Islamist who since taking office in September has promised to support the neglected Sunni minority community, said the army was prioritising the western Sunni province in its fight against Islamic State.

“The Iraqi government and security forces are extremely concerned with Anbar, its defence and the protection of its residents from Daesh,” he said on his official Facebook page, using a pejorative acronym for the ultra-radical Sunni group.

An Iraqi military official in Baghdad told Reuters that the insurgents had taken advantage of a lull in the air strikes caused by poor weather to launch the offensive, but that weather had since improved.

The US military said the United States and its coalition partners conducted seven air strikes against Islamic State militants in Iraq between early Thursday and early yesterday, including five strikes about 15 kilometres east of Ain al-Asad base.

The Iraqi official said that Islamic State had been cleared from most of al-Baghdadi, with the remaining fighting centred around a police station.

That conflicted with reports from a tribal leader who said the jihadists were still in control of much of the town.

Ongoing clashes and poor communications in the area made it difficult to confirm such reports.