Australian Foreign Minister Julie Bishop says about 110 Australians are fighting with Isis (Islamic State) in Iraq and Syria and concern is turning to what to do with them if they survive and return home.

"It now seems that as Isis comes under increasing pressure in both Iraq and Syria, and particularly as a result of the Mosul offensive, there is a high risk that more foreign fighters will seek to leave and will try to return home including in our region and to Australia," she told the Herald today during a brief visit to Auckland.

"So monitoring and disrupting their movement will take an international effort and most certainly Australia is playing its part."

Australia was working closely with other countries including Indonesia, Malaysia and the Philippines to ensure they shared intelligence, strategies and experience in dealing with foreign terrorist fighters.


She had discussions yesterday with Foreign Minister Murray McCully and today with Prime Minister John Key.

New Zealand and Australia - with 100 and 300 troops respectively - have trained 12,000 Iraqi troops at Camp Taji near Baghdad, many of whom are taking part in the offensive to reclaim Mosul, which ISIS seized two years ago.

Bishop said around 110 Australians were currently fighting or engaged with the terrorist groups in Syria or Iraq.

"We believe a number have already been killed and there are about 200 people in Australia who are being investigated for terrorism-related activity."

Indonesia had between 500 and 700 foreign terrorist fighters in Iraq and Syria.

She said about 180 Australian passports had been cancelled on security grounds.

"I have refused to issue about 25 passports on security grounds and I think we have suspended about 30."

In 2014 John Key said five New Zealanders were among the foreign fighters and 30 to 40 New Zealanders were on a security watchlist as potential foreign fighters, with another 30 to 40 needing to be investigated.

A New York - based intelligence specialist, TSG, estimated 10 months ago that of the 27,000 to 31,000 foreign fighters, up to 10 were from New Zealand.

New Zealand's training deployment to Iraq has been extended for 18 months to November 2018.

The Australians have no deadline and Bishop said it would not be helpful to put a timeframe on it.

"We are there at the invitation and consent of the Iraqi Government," Bishop said.

"Our mission in Iraq is to advise and assist and build the capacity of the Iraqi security forces to the point where they can regain control of Iraq security.

"When the job has been completed then we'll leave."

Asked if there could be a role for a New Zealand and Australian civilian force to help rebuild Iraq post-ISIS, she said it was up to the Iraqi Government.

"If they asked, of course we would consider it."

Defence Minister Gerry Brownlee leaves New Zealand tonight for a meeting in Paris of countries in the anti-ISIS coalition to discuss what happens in Mosul after it is regained.

It will also focus on foreign fighters.

The Taji trainers have been mandated to train an Iraq stabilisation force - essentially armed police - but that has not yet been called upon by Iraq.