There is no support among world leaders for the prospect of a US-led army in Iraq and Syria to take back ground from Islamic State militants, Australia's prime minister said Tuesday.

Prime Minister Malcolm Turnbull said in a speech to Parliament on national security that his government did not intend to change Australia's military commitment to Iraq and Syria in response to the Paris attacks as well as the recent attacks in Africa and Lebanon. Australia's contribution of fighter jets in Syria and Iraq and military trainers in Iraq is one of the largest among the 60-nation coalition.

Turnbull said his recent discussions with world leaders at the G-20, APEC and East Asia Summit forums found that "there is no support currently for a large, US-led Western army to attempt to conquer and hold ISIL-controled areas."

"In Syria, the broader conflict and the absence of a central government that the West can work with makes action against ISIL even more complicated," Turnbull said.

Some government lawmakers have advocated sending ground troops into Syria. The Iraqi government does not allow Australian troops to operate off base in Iraq.

But Turnbull said "the unilateral deployment of Australian combat troops on the ground in Iraq or Syria is not feasible or practical."

There have been three attacks in Australia since September last year when the terror threat level was raised to the second-highest level on a four-tier scale. That means the government considers a terrorist attack is likely.

Turnbull said a new five-tier scale would be introduced this week that would provide the public with more information on the nature of the threat.