The Port of Melbourne sale could run into strife in the Victorian upper house amid concerns Labor has scotched the possibility of a second major container port in Victoria to maximise the short-term price.

On Wednesday morning, Treasurer Tim Pallas said the plan to offer a 50-year lease on the public asset would conservatively net up to $6 billion to plow back into productivity-boosting transport infrastructure.

But in apparent attempt to make the deal as attractive as possible, any future government introducing added competition by building a second container port – potentially either at Hastings or on the other side of the bay near Werribee – could be forced to pay compensation to the new operator.

The proceeds of the port's sale will be used to fund the government's two-term commitment to remove 50 level crossings, among other transport promises.

Mr Pallas said the returns from the lease transaction offered an opportunity to significantly boost productivity by putting the proceeds back into transport infrastructure.