The Government is being accused of pork-barrel election bribes if it fast-forwards a second harbour crossing in Auckland without doing a proper economic analysis.
Auckland MP and Labour's transport spokesman Phil Twyford said he had been leaked information that Prime Minister John Key will make an announcement on the second crossing on August 12 - and it will be roads-only, with no rail option.
"It's a $5 billion project, a major piece of transport infrastructure. They're going to announce that they're going to bring it forward.
"It's currently on the books in the Auckland Plan to be built late in the 2020s. It has a 0.3 benefit-cost ratio (30c return for every dollar invested). So it's hard to see the numbers stacking up to build the second harbour crossing immediately. And there's a strong view in Auckland that it should include rail and roads."
Mr Twyford said his source did not know how far forward the Government wanted to bring the project.