FEDERAL MP Justine Elliot has slammed the state government for reneging on an election promise to provide half of the funding for the Pacific Hwy upgrade.

Funding for the Pacific Hwy is a highly controversial and confusing subject, with state and federal governments giving conflicting information on the funding split.

Both Mrs Elliot and federal infrastructure and transport minister Anthony Albanese maintain that in 2006, a NSW coalition opposition promised to divide the funding in a 50:50 split to ensure the upgrade could be completed by 2016.

However NSW Roads and Ports minister Duncan Gay wants to see the current 80:20 funding split afforded to the previous state Labor government continued.

While Mrs Elliot has reassured Tweed residents the funding for the upgrades at Banora Point and between Tintenbar and Ewingsdale are already secured, she said the coalition's failed promise raised fears for the remainder of the project.

"It is extremely disappointing that now when they are in government, the National Party members are resiling from their position to match the funding provided by the federal government," Mrs Elliot said.

"It would be very alarming if the full duplication of the Pacific Hwy was jeopardised by the NSW coalition government abandoning their prior commitments."

She said she had secured $554 million for the Tintenbar to Ewingsdale upgrade and $349 million for the Banora Point upgrade, with a further $10 million coming from the state government.

State member for Tweed Geoff Provest spoke up in parliament this week saying the funding between the federal and NSW governments should continue as an 80:20 split.

He accused the federal government of putting politics before the safety of motorists.

"The NSW government supports the Prime Minister's goal of completing the duplication of the highway by 2016," Mr Provest said.

"Under this federal government, the funding between the federal and NSW governments has always been an 80:20 split.

"Mr Albanese is now seeking to reduce his government's funding and force the NSW government into a 50:50 share of the cost of upgrade.

"This is a complete shift from the current funding agreement."

Mr Provest said a 50:50 funding shift would be "manifestly unfair."

"Considering the Commonwealth's large revenue base and its expenditure on projects such as the National Broadband Network, an estimated $36 billion, and the Building the Education Revolution, $16 billion, surely the Federal Government can find $2.3 billion to upgrade the highway," he said.