Prime Minister Tony Abbott says cabinet and UN endorsement will be sought before Australian military forces go into Iraq to fight Islamic State terrorists.

Australian special forces and aircraft won’t be sent into Iraq until cabinet considers a risk assessment and the United Nations gives the operation the nod.

The first of 600 Australian Defence Force members will deploy to the Middle East within days, to prepare to be part of an international effort to disrupt and degrade Islamic State extremists, also known as ISIL.

The deployment will include up to eight F/A-18F Super Hornet aircraft, refuelling and control aircraft, special forces and logistics experts.

Prime Minister Tony Abbott said the government had so far only made a decision to pre-deploy forces to the United Arab Emirates.

It had “a mind” to commit to combat operations under the right circumstances but that decision would be made after a full assessment of the risks.

Such a move would also require a written invitation from the new Iraqi government and the approval of UN leaders holding talks in New York next week.

“It is after that meeting takes place, after the coalition has crystallised, that final decisions are likely to be made,” Mr Abbott said.

Asked whether Australia was now at war, the prime minister said it was a different situation from 11 years ago when the Australian Defence Force deployed to Iraq.

“It’s a mission to be ready to join an international coalition … with a humanitarian objective,” he said.

While Labor has given bipartisan support, Greens leader Christine Milne said the government had no clear objective and owed it to Australians to spell out a timetable for the mission.

Mr Abbott has said the mission will “not be over in weeks or a few months” but there was a very specific objective to destroy IS and drive it out of Iraq.

He declined to rule out extending the mission to Syria, where IS is also engaging in terrorism.

Attorney-General George Brandis is due to introduce a second tranche of anti-terrorism laws to parliament next week, which Mr Abbott said would enable the prosecution of Australian jihadists returning home.

Local Muslim leaders have denounced IS, but do not support the ADF mission, saying it could lead to more people being radicalised.

“These criminals are committing crimes against humanity and sins against God,” said the Grand Mufti of Australia, Ibrahim Abu Mohammad.

Forced eviction, threats of execution and burning of places of worship including churches had no place in any faith, he said.

Palmer United Party senator Jacqui Lambie said advocates of sharia law – moderate elements of which guide Muslim families, but whose extreme aspects include stonings and executions – should leave Australia.

But Mr Abbott, citing a rally in Sydney at the weekend, said he did not doubt the commitment of migrant communities to Australia.

Independent MP and former defence analyst Andrew Wilkie said the mission had public support, but would make Australia “more of a target” for terrorism.

Security agencies have raised the terrorism alert level to high, meaning an attack is “likely”.