Australia has not been asked to increase its military contribution to the fight against the Islamic State (IS) group in Iraq and Syria, according to Foreign Minister Julie Bishop.

Key points: Ms Bishop says current Australian military contribution to fight IS is "appropriate"

Ms Bishop says current Australian military contribution to fight IS is "appropriate" Expected to touch on conflict in meeting with Secretary of State Rex Tillerson

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Ms Bishop described her hour-long meeting with United States Vice-President Mike Pence as "warm" and "constructive" with the pair discussing the refugee resettlement deal and tensions in the South China Sea.

The Foreign Minister said Mr Pence spoke of Australia's military contributions in "the most positive terms" and praised the strength of the alliance.

"Australia is already one of the major contributors to the effort to defeat IS in Iraq and Syria and indeed at one point we were the second-largest contributor after the US," Ms Bishop said.

"I believe we are now the third-largest contributor and we have been there from the outset.

"We have not been asked to change our contributions, our contribution is appropriate."

On Monday, US-backed forces launched a large-scale military operation to dislodge IS militants from the western half of Mosul in Iraq, which has been in the hands of extremists since 2014.

Ms Bishop said she discussed the fight against IS in "general terms" and provided her contribution to a broader review of the strategy to defeat the group.

"Clearly we want to be a part of the strategic thinking of the US because we have been a major contributor to the Coalition to defeat IS and we will continue to do so," she said.

"This affects Australia and our security; the number of foreign terrorist fighters leaving Iraq and Syria as more gains are being made against them is a concern for our region."

Ms Bishop said Australia's military contribution would always be under review but described current deployments as "appropriate".

Tillerson meeting to also touch on Middle East conflict

Australia formally declined a request from the US to increase its military commitment in the Middle East early last year.

At the time, the Turnbull Government would not commit to the request but stressed Australia would continue to play an important role in the region.

Ms Bishop will meet with US Secretary of State Rex Tillerson tomorrow and is expected to discuss the conflict in more detail.

"This is an opportunity for us to make known Australia's interests and priorities and of course we share common values and interests with the United States," she said.

"I have already had a long telephone conversation with Secretary Tillerson, it was very positive and I expect that we will continue that discussion."

Australians close to Mosul

Australian training forces are now working closer than ever to the war-torn city of Mosul in Iraq.

Australia has been taking part in air strikes against the Islamic State group in Mosul, as well as providing training and medical support to Iraqi forces fighting in the city.

Chief of joint operations Vice Admiral David Johnston said Australian medics and special forces were now operating within 50 kilometres of Mosul.

"We have been moving to the forward operating bases, as to do the advise and assist function you need to be with senior Iraqi leaders who are coordinating the battle on the ground," he said.

"That has meant we have needed to move with them."

Vice Admiral Johnston said the Defence Force had taken steps to ensure there was no repetition of botched air strikes which killed Syrian forces last year.

Two Australian hornets dropped six bombs as part of strikes which killed dozens of Syrian forces in September.

A US-led military investigation blamed "unintentional human errors" and said coalition partners would improve information sharing.

"The work to improve those processes has been underway since that investigation — it started well before it was concluded and we've been a close part of monitoring that to satisfy ourselves that the right action has been taken," Vice Admiral Johnston said.