Opposition Leader Tony Abbott has refused to say whether his $1.5 billion commitment to the WestConnex road project in Sydney remains contingent on it including a final link to the CBD.

Yesterday Prime Minister Julia Gillard promised an unspecified amount of Commonwealth funding for the motorway, as long as it connects through to the city and the port, and does not include tolls on roads that are currently free.

The announcement created a new stoush between Ms Gillard and NSW Premier Barry O'Farrell, who said the Prime Minister's demands would add up to $8 billion to the project, which is already estimated to cost between $10 billion and $13 billion.

Mr Abbott responded to the announcement yesterday, saying: "I think what the Prime Minister has done today has set up a new fight with the State Government, not a real commitment to actually make this thing happen."

In January Mr Abbott told News Limited it was not good enough the WestConnex project did not include an expressway through to the city.

"The WestConnex project is still evolving but we'll ensure there's an expressway-standard road from the west to the city as part of our commitment. It has to be in there," he was quoted as saying.

Asked today whether that remained his position, Mr Abbott sidestepped the question and instead focused on Ms Gillard's announcement.

"What the Prime Minister was doing yesterday was not committing to get it built, she was committing to have a fight," he said.

"She was setting up yet another stage-managed, carefully choreographed, world championship wrestling-style fight with a state government."

When pressed twice more to explain his position, Mr Abbott responded: "Obviously we want to see the best possible infrastructure but we want to see something happen soon."

Asked to clarify

During the same press conference, Mr Abbott was also asked to clarify comments he made yesterday about the Coalition's commitment to repeal the carbon tax.

"When you get rid of the carbon tax, you don't need the carbon tax compensation. Now, we'll certainly keep paying a substantial proportion of that - exactly how much, we'll say closer to the election," he said yesterday.

Mr Abbott would not explain what that meant but repeated his assurance that families would be better off under a Coalition government.

"They will know in good time before the next election exactly what the consequences of our policies will be," he said.

Asked to clarify the Coalition's position, shadow treasurer Joe Hockey said: "If there's no carbon tax, there's no need for compensation.

"If you don't have carbon tax, you don't have injury.

"(Families) won't have a carbon tax and there will be payments to families in the form of welfare payments and there will be tax cuts based on the tax levels without the carbon tax package."

But he says the Coalition will not make funding commitments until it has seen the "state of the books", referring to the Pre Election Fiscal Outcome (PEFO) which is released during the formal election campaign.

'Complete mess'

Climate Change Minister Greg Combet has described the Coalition's climate change policy as a "complete mess", saying pension increases and tax cuts would be under threat if the Coalition won the election.

"The Coalition's policy in this area is a complete shambles. And they're trying slippery tactics of not specifying what it is. But now we know," Mr Combet told reporters.

"Joe Hockey's come out and conclusively said that there'll be no compensation kept that followed the introduction of the carbon price.

"He's conclusively said that they'll be increasing taxes for low and middle income earners.

"Conclusively said that they'll be cutting the pension.

"Conclusively said that they'll be cutting Family Tax Benefits for people."

Mr Hockey has previously had to correct statements he made about the Coalition's carbon pollution policy, when he suggested there would be compensation for businesses that would be worse off if the carbon tax was scrapped.