Opposition Leader Tony Abbott has dismissed the Federal Government's budget pledge for Brisbane's Cross River Rail plan.

Last week, Treasurer Wayne Swan promised $715 million for the $5 billion project.

But federal Labor is locked in a funding stoush with the Queensland Government.

Member for Griffith Kevin Rudd says the State Government is playing politics with the budget offer, which was precisely what it had asked for.

Meanwhile, west of Brisbane today, Mr Abbott has said the Federal Government is not being "fair dinkum".

"It's more of the kind of wild stuff that we get from a desperate Government," he said.

"Now, our position is that the number one infrastructure priority for the Commonwealth here in Brisbane is the Gateway Motorway upgrade.

"We've committed $1 billion to that."

The Queensland Government says some of the promised funding would end up redirected through the GST process.

Treasurer Tim Nicholls has described the funding pledge as smoke and mirrors.

'Deeply political'

But the Federal Government says it is based on a dollar-for-dollar deal it struck with State Transport Minister Scott Emerson.

Mr Rudd says the project is vital to take pressure off Brisbane's Story and Captain Cook bridges.

He revealed correspondence he says proves the State Government has been offered exactly what it sought.

"What has happened here is deeply political and it's got nothing to do with the truth," he said.

"What they've done is to try and rewrite the history, rewrite how much they asked for, rewrite the conditions under which they sought that $750 million and here's their problem - it's here in black and white."

Mr Rudd says Mr Emerson wrote to Federal Infrastructure and Transport Minister Anthony Albanese, asking for a contribution "estimated in the order of $750 million dollars and that this would be matched by the Queensland Government".

"One letter from Scott Emerson in his own handwriting, signed, and one from Albo's office going back to him saying we accept all your conditions, including on the GST," Mr Rudd said.

Gesture, not policy

The Federal Opposition has promised no funds for the project.

Speaking today at Ipswich, west of Brisbane, Mr Abbott has said the Federal Government's offer is not genuine.

"If it was fair dinkum, it would have made a commitment that actually enabled the thing to go ahead," he said.

"And as the State Government has made crystal clear, the commitment as it stands is not enough to make it go ahead so it's really a gesture, not a policy.

"It's more of the kind of wild stuff that we get from a desperate Government.

"Now, our position is that the number one infrastructure priority for the Commonwealth here in Brisbane is the Gateway Motorway upgrade.

"We've committed $1 billion to that."

Mr Abbott says that project will be underway "within 12 months of a change of government".

The Federal Government has also committed $718 million for the Gateway Motorway between Nudgee and the Bruce Highway.

Mr Emerson has pledged to lobby both sides of politics for federal funding for the Cross River Rail project.

He has previously expressed disappointment that the Federal Coalition had pledged no funding.

But Mr Abbott says the Commonwealth should only pay for major road and freight rail projects, to avoid funding fights between federal and state governments.

"We should stick to that which we have traditionally done, so that the Commonwealth does its thing, the state does its thing and we don't have the kind of opportunities for buck-passing and blame-gaming that have flourished under this Government."

The Cross River Rail project involves running trains under the Brisbane River between Yeerongpilly and Victoria Park.

The proposed funding arrangements would also require contributions from the private sector.