Australia Monday morning sent a second RAAF aircraft from Darwin to join the search for a Malaysia Airlines Boeing 777-200ER that has been missing since early Saturday.

Australia sent an RAAF AP-3C Orion on Sunday night and a second aircraft left Darwin at 8.30 am (AEDT) on Monday, the Australian Associated Press reported.

Air Marshal Mark Binskin said the maritime patrol and long-range surveillance aircraft were equipped with sensors and electro-optic detectors that were ideal for the operation.

There are 18 Australian crew on board each RAAF jet.

Six Australians and two New Zealanders, one of whom lives in Perth, were on the MAS plane that disappeared over the South China Sea early Saturday morning, one hour into what should have been a six-hour flight from Kuala Lumpur to Beijing.

Authorities are examining links to terrorism as two of the flight's 227 passengers were found to have used stolen passports.

Australian Foreign Minister Julie Bishop has been in touch with her Malaysian counterpart to offer Australia's support.

She said the reports of stolen passports were concerning.

"There may be no connection at all but it is a worrying development," Bishop told ABC radio on Monday.

"Our officials are in urgent and ongoing contact with authorities in Malaysia."

Malaysia has set up a rescue co-ordination centre and dozens of ships and aircraft were looking for the missing aircraft, she said.

China, the Philippines, Singapore, the United States and Vietnam have also sent resources to join the search.

Families of the Australians on board were receiving consular assistance, Bishop said.

MAS Flight MH370, carrying 227 passengers, including two infants, and 12 crew, went missing en route from Kuala Lumpur to Beijing about an hour after taking off from the KL International Airport at 12.41 am on Saturday.

It should have landed in Beijing at 6.30 am.