The cash-strapped Turnbull government has been accused of reneging on an infrastructure funding deal after Victoria secured a $9.7 billion windfall from the lease of the Port of Melbourne.

The bigger-than-expected gain from the 50-year lease will allow the Andrews government to unleash billions of dollars for road and rail projects in the lead-up to the 2018 election.

The government was also expecting a further $1.45 billion for infrastructure under the federal government's asset recycling scheme, offering payments equivalent to 15 per cent of the sale price for public assets, provided the proceeds are reinvested in productive infrastructure.

But Treasurer Scott Morrison's office said Victoria would get only $877.5 million – equivalent to 9 per cent of the price – claiming Victoria had failed to finalise a deal by June 30.