The federal and South Australian governments are at odds over transport funding in Adelaide with a minister accusing the commonwealth of reneging on promises and targeting the Labor state.
Two major rail projects are at risk with the federal government indicating it will not provide about $100 million in previously promised money.
State Infrastructure Minister Tom Koutsantonis said the decisions made a "joke" of Prime Minister Tony Abbott's desire to be known as the infrastructure prime minister and would cost jobs.
"We had an agreement. We had a deal," Mr Koutsantonis told reporters on Thursday.
But federal Assistant Infrastructure Minister Jamie Briggs said the incoming government had made it clear that its focus would be on building roads rather than urban rail.
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He said the coalition was committed to funding the north-south road corridor through Adelaide but if the state government had committed to rail projects based on federal assistance, it had done so at its own risk.
"The state government was told very clearly they needed to consult and get approval from the federal government prior to signing contracts," Mr Briggs said.
"This state government seems to want to have a political fight.
"That's fine, but at the end of the day we want to deliver the roads of the 21st century for South Australians."
Mr Koutsantonis said in relation to one of the rail projects, Mr Abbott had told Premier Jay Weatherill that the new government would honour any contracts that had been signed before the election.
He said contracts had been signed and work was underway with some money already received from the commonwealth.
"It's an example of what the Abbott government is going to be like. They're cutters, these guys aren't builders," Mr Koutsantonis said.
"They're happy to target Labor governments. That's not how you govern. You govern by need, not by politics."
The rail projects, upgrading and duplicating the suburban Tonsley line and electrifying the line from Adelaide to suburban Salisbury, are part of the state government's $36 billion, 30-year transport plan which was unveiled earlier this week.
The strategy will require significant and ongoing federal funding.