Kevin Rudd has been sworn in as prime minister of Australia on Thursday following his victory in a ruling Labor party caucus ballot the evening before.

Governor-General Quentin Bryce, acting on the advice from the solicitor-general, swore in Rudd in a brief ceremony at Government House in Canberra on Thursday.

Bryce wished him well in serving the people of Australia and Rudd replied "I will do my absolute best."

This is the second time for Rudd to serve as Labor prime minister after he was overthrown by his then deputy Julia Gillard on June 24, 2010.

Also sworn in on Thursday were Anthony Albanese and Chris Bowen, two key Rudd supporters in the Labor party, as deputy prime minister and treasurer respectively.

Rudd is expected to announce more of his cabinet lineup in the following days as some key cabinet members quit after then Prime Minister Gillard lost to Rudd in the caucus ballot by a 12 vote margin.

Among those who have resigned from the cabinet are Deputy Prime Minister and Treasurer Wayne Swan, Minister for Trade Craig Emerson, Minister for Communications Stephen Conroy and Minister for Agriculture Joe Ludwig.

The swearing-in by the governor-general secured an assurance from Rudd that he would announce his appointment to the House of Representatives on Thursday.

The parliament would then be able to take whatever action it chose to do, including a no confidence motion.

But opposition leader Tony Abbott played down the possibility of calling for a no-confidence motion in the Labor government.

"Plainly one-third of the cabinet has no confidence in Mr. Rudd, they've resigned. It's the biggest exodus from the cabinet in memory," Abbott told the Nine Network, "But we're not into parliamentary games ... let's let the people decide."

Australian Associated Press said it appeared likely Australia will go to the polls earlier than planned Sept.14 election with Aug. 24 a possible date.

Minister for Finance and Deregulation Senator Penny Wong, who was elected Labor's new leader in the Senate, said she voted for Rudd because "I had to decide who I thought would offer the best contest at the next election against Tony Abbott."

"The party will unite behind Kevin Rudd's leadership," Albanese said.