Islamic State: Tony Abbott says sending 300 troops to Iraq is not 'mission creep', refuses to rule out further increases

Prime Minister Tony Abbott has rejected suggestions that sending another 300 troops to Iraq amounts to "mission creep" and has not ruled out future increases in Australia's contribution to the fight against Islamic State.

Mr Abbott announced the boost to Australia's commitment after discussing the decision with Cabinet and Government backbenchers this morning.

"It is critical for Australia just as it is critical for the wider world that this death cult, this apocalyptic millenarian death cult be disrupted, degraded and ultimately destroyed," he said at a press conference, flanked by the Defence Minister and the Chief of the Defence Force.

The mission was flagged across the Tasman last week, when New Zealand's prime minister John Key announced that more than 140 of the country's troops would be sent to Iraq as part of a new mission with Australian defence personnel.

Australia joined the international effort to defeat Islamic State (IS) militants in September, with a contribution of six F/A18 fighter jets, a surveillance aircraft, a refueller, 200 special forces soldiers and 400 military support staff to the US-led mission.

Mr Abbott said the additional troops, who will be set to work training Iraqi soldiers, marks a necessary "next phase" in Australia's involvement.

"It's not mission creep, it's the successful execution of the original mission," he said.

However, he would not detail the specific task the deployment needed to complete to be deemed a success.

"I'm not going to be too prescriptive at this stage. What we want to do is help to train an effective Iraqi regular army," he said.

"We will review progress and obviously the key indicator here is how effective are the Iraqi armed forces? How effective is our mission to ensure that these armed forces are capable of doing their job?

"It is a mission which is necessary, because obviously in the face of the initial death cult onslaught, the Iraqi regular army melted like snow in summer."

'This is a conflict which is reaching out to our shores'

Mr Abbott said Australia needed to "do its bit" for security abroad to boost security at home.

"This is a conflict which is reaching out to our shores and has already been the inspiration for two terrorist incidents and another potential terrorist incident that was only hours away from taking place," he said.

"So people want to be secure, but in order to be as secure as we can be at home, it's important that we actually do what we can to disrupt and degrade this scourge at its source."

Greens leader Christine Milne tried to force Parliament to debate the deployment, but Government and Labor MPs voted down the motion, as they did last year when the first troop commitment was announced.

"This will be a mission creep, this will see us engaged in a quagmire in Iraq on the back of a captain's call," Senator Milne told Parliament.

"Sending Australian troops, men and women, we're now going to have 900 of them there, and to what end? For what purpose?"

The Prime Minister said the new "training force" would be ready to start work in June and the mission would be reviewed after 12 months.

He said "at this stage" the mission would last for two years but could not rule out further announcements increasing Australia's commitment.

"It would be wrong of me to say that this is the last that we will do here, but nevertheless what we are doing at this stage is prudent, it's proportionate," he said.

"It builds on what's already been done and I think it has every chance of being effective."

The new force, to be drawn from the regular forces, will be based at Taji, north-west of Baghdad.

The Prime Minister also said that about 170 special forces, mostly based at Baghdad International Airport, would come home in September.

'I can't go out and fight with them, but I try to sweat with them'

Prime Minister Tony Abbott and Opposition Leader Bill Shorten both paid tribute to the troops and their families in Parliament.

"I obviously can't go out and fight with them but, Madam Speaker, I try at least to sweat with them," Mr Abbott said.

"Which is one of the reasons why I've tried so often to have physical training at the very least with the members of our armed forces when I am on their bases."

Labor has given the plan conditional bipartisan support, saying Australian troops must be in Iraq at the request of the Iraqi Government, but must not operate beyond Iraq's borders and ground combat units must not be deployed.

The Opposition also wants to ensure that Australia would withdraw its support if Iraqi soldiers were found to engage in unacceptable conduct.

Mr Shorten, who was briefed on the plan as the Prime Minister made the announcement, said the new training mission met Labor's criteria.

"It appears from the information that was provided to us that the commitment most certainly likely accords with Labor's principles and the scope of activities that we've outlined," he said.

"There have, of course, been some troubling reports regarding the behaviour of some Iraqi militia groups and of course we know that our military and our ADF and our Foreign Affairs Department is monitoring this most carefully."