Federal minister Christopher Pyne has branded the new Labor government in his home state of South Australia as “illegitimate” and claims the state electoral commission’s boundaries favour the ALP.

“Jay Weatherill’s government is an illegitimate government,” he told reporters in Canberra on Monday.

Mr Pyne said the Liberals had achieved 53 per cent of the two-party preferred vote in the March 15 state election.

Despite this, the final count gave Labor 23 seats, the Liberals 22 while two being held by independents.

Mr Pyne argued this showed the electorate boundaries were drafted in such a way that Labor could win the election with 47 per cent of the vote.

“That needs to be closely looked at,” he said.

Independent MP Geoff Brock announced on Sunday he would back Labor to form a minority government in South Australia, more than a week after the March 15 poll produced a hung parliament.

In Canberra, federal Labor MP Amanda Rishworth said many had written off Mr Weatherill and Prime Minister Tony Abbott had to take some of the blame for the Liberal loss.

“Tony Abbott just shrugged his shoulders when it came to helping out Holden, when he said goodbye to those jobs,” she said.

Government frontbencher Jamie Briggs said Labor had retained power in South Australia without the majority of the vote and with the support of a conservative independent MP.

“We have seen this show before and we know how it ends,” he said.

Mr Briggs said his state colleagues now needed to bunker down and hold the government to account.

“In four years time they need to present an alternative vision for South Australia and get the majority of seats, not just the majority of votes.”

Queensland Liberal MP Bert van Manen said the decision was disappointing.

“At the end of the day we won 53 per cent of the primary vote so we need to have a look at that as well,” he told reporters in Canberra.