Seven American soldiers have been killed in a military helicopter crash in western Iraq, the Pentagon has confirmed.

The HH-60 Pave Hawk helicopter crashed near al-Qaim, a town in Anbar province close to the Syrian border, yesterday, reportedly after hitting a power line.

The Pentagon says in a statement Friday that the crash does not appear to be the result of enemy activity and is under investigation.

President Donald Trump later tweeted his condolences to the families of the 'brave troops'.

Tragedy: The helicopter crashed near al-Qaim, a town in Anbar province close to the Syrian border yesterday, with all seven U.S. servicemen on board killed in the incident

Condolences: Donald Trump tweeted a message to the families of the servicemen

He posted: 'Our thoughts and prayers go out to the families and loved ones of the brave troops lost in the helicopter crash on the Iraq-Syria border yesterday. Their sacrifice in service to our country will never be forgotten.'

Four of the seven servicemen killed were members of the Air National Guard’s 106th Rescue Wing based at Gabreski Airport on Long Island, according to 27east.com.

'All personnel aboard were killed in the crash,' said Brigadier General Jonathan P. Braga, director of operations of the Combined Joint Task Force.

'This tragedy reminds us of the risks our men and women face every day in service of our nations.'

Crash: The HH-60 Pave Hawk helicopter was not brought down by enemy fire (file image)

The helicopter is used by the Air Force for combat search and rescue, and was in transit from one location to another when it went down Thursday afternoon.

The Pentagon said an accompanying U.S. helicopter immediately reported the crash and a quick-reaction force comprised of Iraqi security forces and Coalition members secured the scene.

The names of those killed will be released after next of kin have been notified, the statement added.

The crash is the deadliest incident involving U.S. soldiers abroad since May, 2013, when seven servicemen were killed by a roadside bomb in southern Afghanistan.

The United States acknowledges that it has about 5,200 troops in Iraq that are part of a coalition fighting ISIS militants.

The US has operated both helicopters and fixed-wing aircraft in Iraq during the war against ISIS, which overran large areas north and west of Baghdad in 2014.

US forces began carrying out air strikes against ISIS in August 2014, a campaign that was later expanded to Syria, and has provided weapons, training and other support to forces fighting the jihadists in both countries.

Baghdad declared victory over the extremists late last year, but ISIS still has the ability to carry out deadly violence in Iraq, including a series of attacks in the country's north that left 25 dead earlier this month.