BAGHDAD: Iraq's counter-terrorism forces backed by army troops and US-led coalition air strikes advanced towards the western town of Hit on Thursday in an attempt to dislodge Islamic State militants, the military said.

A senior officer from the counter-terrorism forces, the elite US-trained units which led the recapture of nearby Ramadi three months ago, said his troops were one kilometre from the town centre, 130 km (80 miles) west of the capital Baghdad.

The recapture of Hit, strategically located on the Euphrates River near Ain al-Asad air base where several hundred U.S. forces are training Iraqi army troops, would push Islamic State further west towards the Syrian border, cutting a connection to the northern town of Samarra and leaving Falluja their only stronghold near the capital.

Baghdad has had success in pushing back the militants in recent months and has pledged to retake the northern city of Mosul later this year, but progress has often been fitful.

Another officer, on a frontline less than 3 km from Hit, said the operation had begun at 0600 (0300 GMT) and was progressing swiftly.

"There are some IEDs along the movement but it's still good to go and we are moving," he said by phone.

In a statement announcing the advance, the military said the offensive was backed by airstrikes from the Iraqi army and air force as well as the international coalition fighting Islamic State in the areas of Iraq and neighbouring Syria where the militants declared a "caliphate" in 2014.

The statement called on civilians in Hit, thought to number in the tens of thousands, to move away from Islamic State positions: "Those targets will be destroyed".

The jihadists have regularly used civilians as human shields, a tactic aimed at slowing the advance of Iraqi forces and complicating air strikes essential to the ground advance.