The Federal Government appears almost certain to next week authorise air strikes in Syria against the Islamic State (IS) terrorist group.

The Government is considering a United States request to expand bombing operations across Iraq's western border into Syria.

"We are taking the request from the United States very seriously indeed," Prime Minister Tony Abbott said.

"We are very determined to play our part in the international campaign against the death cult, which isn't just horribly persecuting people in the Middle East, but which is reaching out to this country."

Cabinet's National Security Committee will make a decision this week and has been waiting for Defence Minister Kevin Andrews to return from overseas to provide a briefing.

The Minister has said he was likely to support the move.

"This is ultimately a decision for the National Security Committee of Cabinet to make," Mr Andrews said.

"However, in light of the circumstances, my inclination is to do this. This is not a radical departure from what we are doing now; it is simply widening our area of operation."

Government frontbencher Mitch Fifield said the Coalition party room would be comfortable with Australia increasing its military commitment.

"We know that IS don't observe the borders that they travel from Iraq into Syria, and at the moment we've been prevented from continuing a mission across that border," the Assistant Social Services Minister told Sky News.

"I think my colleagues in the party room would be very comfortable with doing more to seek to defeat IS."

Super Hornet and 'classic' Hornet fighter bombers would reportedly undertake limited and carefully planned strikes on IS military depots and command posts that launch attacks into Iraq.

Mr Andrews said Iraq would remain the focus of Australian operations.

On Saturday, there were reports France was also considering conducting air strikes against IS in Syria.

'Bombs will make a bad problem worse'

But Greens leader Richard di Natale said bombing would only inflict more misery on Syria.

"Dropping bombs on Syria will make a bad problem worse," he said.

Australia joined the international effort to defeat IS in September last year.

Its contribution currently consists of six F/A-18 fighter jets, a surveillance aircraft, a refueller, 200 special forces soldiers and 400 military staff operating in support of the US-led mission.

Former coalition forces commander David Petraeus encouraged Australia to expand its role, as did former Labor foreign minister Bob Carr.

But critics of the expansion have included former ADF chief Retired General Peter Gration, who said bombing raids would be illegal and disastrous, and Labor's foreign affairs spokeswoman Tanya Plibersek.