Australia rejects US request for more help to tackle ISIS

The nation argued that it had already made a 'substantial' contribution to the fight

Australia has formally rejected a request from the United States for more military help to tackle the Islamic State group, arguing it had already made a "substantial" contribution to the fight.

US Defence Secretary Ashton Carter in December asked coalition partners battling the jihadists and other militants in Iraq and Syria for a greater commitment following the Paris attacks in which 130 people were killed.

Prime Minister Malcolm Turnbull signalled at the time that there was no appetite for such a move and Defence Minister Marise Payne said Australia's current commitment was sufficient.

"Australia has considered the request from US Secretary of Defence Ashton Carter in light of the substantial contributions we are already making to train Iraqi security forces and to the air campaign," she said in a statement late Wednesday.

"The government has advised Secretary Carter that our existing contributions will continue."

The decision comes just days ahead of Turnbull meeting US President Barack Obama in Washington on a trip focused on terrorism and territorial disputes. During the visit, he will deliver a national security address at the Centre for Strategic and International Studies.

Australia has some 780 defence personnel in the Middle East supporting its operation against IS and has been active in Iraq for months.

Many are based in Iraq with 400 attached to the Air Task Group flying six F/A-18 Hornets on bombing missions.

Another 300 are in Baghdad helping train Iraqi security forces while 80 are advising and assisting on counter-terrorism operations with the Iraqi military.

Late last year Australia started carrying out air strikes against IS targets in Syria as part of a 60-nation, US-led coalition against the jihadists.

Payne said that while there would be no change in Australia's current military commitments, it would offer more airlift support on humanitarian efforts while keeping its options under review.

In Australia, authorities have been on alert for potential terrorist attacks since late 2014, when it raised its alert level to high. Canberra has since introduced new national security laws and conducted a string of counter-terrorism raids.

Six attacks have been foiled on home soil over the past year, according to the government. But several have taken place, including the terror-linked murder of police employee Curtis Cheng in October.