CANBERRA, March 25 -- Two Australians were among the 150 people killed overnight when Germanwings flight 4U9525 crashed in the French Alps, Australia confirmed on Wednesday.

A mother and her adult son from Victoria were traveling on the Airbus A320 that crashed en route to Dusseldorf from Barcelona. It is believed there were no survivors.

"I don't think it gets any easier announcing the death of Australian citizens in a tragedy overseas," Foreign Minister Julie Bishop told reporters early on Wednesday morning.

"Our thoughts and prayers and support are with the family of the victims and we will continue to provide them whatever consular assistance they may require."

"It would not be appropriate to disclose further details of our citizens at this stage due to privacy considerations of the family. Further details, as the family agrees to the release of those details, will be made."

Bishop said the government was still investigating whether other Australians traveling on other countries' passports were on the flight.

"(We) are seeking to identify if there were any other Australians - dual nations or permanent residents - on the flight, " she said.

Australia will send a consular official to the south-eastern French town of Gap near the crash site, where a mobile office will be set up, Bishop said. The official will liaise with the French authorities on the recovery effort.

Prime Minister Tony Abbott also expressed his sadness at the tragic crash.

"Our thoughts and prayers are with the friends and families of all those killed but particularly with the loved ones of the two Australians who have lost their lives," Abbott said. "Our consular officials are doing what they can for the families."

Other Australian politicians have echoed the prime minister's message of condolence, with Opposition Leader Bill Shorten labeling the news "absolutely heartbreaking".

Budget airline Germanwings, a subsidiary of Lufthansa, will not release the passenger list until all the victims' families have been contacted.