Mallee National Party MP Andrew Broad has written to federal Infrastructure Minister Warren Truss, asking him to consider the benefits of increasing the axle loading on the Mildura line from the proposed 21 tonnes to 23 tonnes.

Mr Broad said a further upgrade of the Murray Basin Rail Project, planned by the Victorian government at a cost of $416 million, made economic sense.

"Currently the Mildura-Melbourne transit is 14 hours by rail," Mr Broad said.

"Upgrading the line to 23 tonnes would bring it up to the national standard interstate rail network, increasing travel speed capabilities and vastly decreasing transit times.

"The improved productivity, through increased freight frequency would be particularly beneficial to our time sensitive horticultural exports."

He said the line would need to be upgraded, in the future, so it made sense to do so as part of the Murray Basin Rail Project.

"With significant investment in the region's produce, the demand for containerised export is growing dramatically and the 23t axle loading will be essential in managing it," he said.

"But to be a real benefit, you would have to do a full network upgrade, to include Manangatang and Sea Lake.

"If you are going to do the Mildura line, you make sure the associated linking lines are done as well."

Mr Hosking said lines running part of the way out of the major ports were able to carry 23t wagons, so a full upgrade would allow for a seamless supply chain.

"It's up to the federal government to spend the money on it,” he said. “But from the return in dollars to the growers pocket and back to rural communities, I would say it is a no-brainer

"It's probably the most cost effective $100 million the federal government could spend on rural infrastructure, at the moment."

The upgrade would lift capacity by 10 per cent for a 2500t train, taking 10 trucks off the road. 

But a spokesman for Mr Truss was reticent to say whether or not the federal government would commit to funding the upgrade.

"The Australian government was not consulted prior to the Victorian government's announcement," the spokesperson said.

"The Department of Infrastructure and Regional Development only received the business case for the proposal two weeks ago and understands that the Victorian government has sent the business case to Infrastructure Australia for review," the spokesperson said. 

The spokesman said the government would consider the proposal, in line with the official processes.

"Meanwhile, we note that this rail line is not part of the Australian Rail Track Corporation (ARTC) network so it would normally be a state only responsibility," they said.

"This, along with Victoria's infrastructure program being in limbo since the Andrews government aborted the East West Link, will be major issues to work through in considering this request."

Mr Hosking said it didn't appear to put Mr Broad at odds with his colleagues.