The Victorian government says there is no cost blowout in its $500 million plan to get trucks off Melbourne's West Gate Bridge.

News Corp Australia has reported Victoria asked the federal government for $680 million for the distributor project just weeks after taking power.

But Attorney-General Martin Pakula said the disparity resulted from the Commonwealth asking Victoria to come up with additional “shovel-ready” infrastructure projects.

He said the state had put forward a number of advanced proposals – one of these was to put extra lanes on the West Gate Freeway.

“There is a project that has been put to us as shovel-ready, it is extra lanes on the West Gate, and we have included that along with a range of other projects,” Mr Pakula told ABC radio on Thursday.

“The claim that the West Gate distributor costs any more than what we said it would is just incorrect.”

Mr Pakula said the extra lanes were “never within the scope of the original distributor project”.

But Labor’s pre-election policy document shows extra lanes were part of the West Gate distributor project, which was costed at $400-$500 million.

Opposition Leader Matthew Guy said Labor was already showing it couldn’t manage major projects.

“Labor now says their own policy document is a lie,” Mr Guy said on Twitter.

A plan to get 5000 trucks a day off the West Gate Bridge is being expanded – not blowing out, the Victorian government says.  Labor promised $500 million to build the West Gate distributor and add new lanes to the West Gate Freeway.

But the state government reportedly asked the federal government for $680 million to build the road.  Premier Daniel Andrews says the increased cost reflected a change to the project.

“This is an initial presentation to the Commonwealth about one option where you could expand the scope of the project,” Mr Andrews told reporters on Thursday.

Mr Andrews said the original proposal included lane management technology to use service lanes to fit more vehicles.

He said the updated proposal included the option of actually building more lanes.

Opposition Leader Matthew Guy said the plan had always included the new lane option, and Labor had lied about the true cost of the project.

“Labor were very clear going into the election that it wouldn’t cost more than $500 million, and now we find them begging the federal government for more money,” he said.

The state government submitted a list of infrastructure options to the federal government to spend $3 billion previously set aside for the dumped East West Link road tunnel project.