Wellington, May 26 (IANS): New Zealand Prime Minister John Key on Tuesday dismissed calls to pull New Zealand troops out of Iraq as Islamic State (IS) militants advanced to within 100 km of their base.

Key told Radio New Zealand that his defence and national security advisors had informed him that New Zealand troops at Camp Taji, just north of Baghdad, were in no greater danger after IS forces overran Ramadi.

But the situation was being constantly monitored by the New Zealand Defence Force (NZDF) and if it changed the government could withdraw the soldiers.

"There's a thorough process that we go through, there are officials that meet and there's early warning systems of making sure that if the situation needs to be reviewed it will reviewed," Xinhua news agency quoted Key as telling the radio station.

"But none of those have been triggered and at this point there's no likelihood they'll be triggered."

However, opposition lawmakers said the IS advance, along with US Defense Secretary Ashton Carter's criticism that Iraqi forces lacked the "will to fight", emphasised the futility of the NZDF's mission.

Taji, where New Zealand and Australian troops run a joint mission to train Iraqi government forces, was now within striking distance of the IS just 100 km away, said the main opposition Labour Party.

"There are now risks of not only rocket and artillery assaults on the base using captured United States equipment, but the camp being surrounded," Labour defence spokesperson Phil Goff said in a statement.

"The Iraqi soldiers' lack of will to fight is due to poor leadership and corruption so extensive they often don't get equipment and supplies," said Goff.

"Dealing with these key problems are outside the ability of our troops."

The opposition Green Party said the government should pull New Zealand troops out of the "Middle East quagmire".

"The premise of New Zealand's military commitment is training the Iraqi army. It is clear the Iraqi army is not equipped or prepared to fight the Islamic State, so why are we there?" Green Party defence spokesperson Kennedy Graham said in a statement.

"With the exception of self-defence, New Zealand should never support any military action that is not explicitly authorised by the UN Security Council and within international law."