Australia is expected to confirm an increase in troop numbers to be sent to Iraq to help train Iraqi security forces to fight the Islamic State group.

Media reports that Cabinet had on Monday night approved the deployment as part of a joint Australia-New Zealand training mission foreshadowed by the New Zealand government last week.

The joint mission will reportedly number around 400 troops, including 143 New Zealand personnel already announced by New Zealand Prime Minister John Key.

Foreign Minister Julie Bishop refused to confirm Cabinet's decision, but said Prime Minister Tony Abbott would be making an announcement on the deployment later Tuesday.

Australia already has 200 special forces troops in Baghdad advising and assisting Iraqi security forces. No Australian troops are to operate in independent combat roles.