The Victorian Government is optimistic legislation to privatise the Port of Melbourne will finally pass State Parliament this week, after months of delays.

Key points: Melbourne's port sale is expected to yield $6b

Melbourne's port sale is expected to yield $6b Government is optimistic legislation will pass this week

Government is optimistic legislation will pass this week Port sale expected to take place after July

Port sale expected to take place after July Greens, farmers concerned about higher fees to use the port

The port is one of Victoria's last remaining public assets and is expected to fetch about $6 billion.

A bill to sell the port's 50-year lease was blocked in the Upper House last year because of a clause that would compensate the new owner if a competing port was developed.

Confidential negotiations with the Coalition to pass the bill progressed over summer, but the Government refused to abandon the compensation clause entirely.

Treasurer Tim Pallas said concessions had been made in confidential negotiations with the Opposition, but the compensation clause would stay in some form.

"We cannot lease an asset without warranting its value, and no investor would see that as being a sensible course of action," he said.

"I think that would substantively devalue the asset for the state of Victoria."

Opposition spokesman Michael O'Brien said the Liberals wanted to see the port privatised, but had not reached a suitable agreement with the Government over compensation.

"What is important is that we don't today stop any future government for the next 50 years being able to make a decision to invest in a new port, a second port, when it's the right time for Victoria," he said.

"We just don't think that any future government for the next half a century should be subject to decisions made by Labor today if they're not in the interest of Victoria."

The Government had wanted to put the port to the market by the end of March but now concedes that will not happen until the second half of the year.

But Mr Pallas said that was not expected to affect the port's sale price.

"Certainly I don't think the marketplace is being over-burdened with offerings from other states," he said.

"The Port of Melbourne is the largest container port in the nation."

Labor wants to use the proceeds of the port sale to remove 50 level crossings.

Port of Melbourne's future capacity questioned

While the Government is selling a 50-year lease, the likely lifespan of the asset is much shorter.

Some experts believe the port will reach capacity before the 50-year lease ends. ( AAP: Julian Smith )

That would mean a second container port for Melbourne, slated for either Hastings or Bay West near South Werribee, would need to be developed sooner rather than later.

Dr Hermione Parsons from Victoria University's Institute for Supply Chain Logistics said there had been great debate about when the Port of Melbourne would reach the end of its life span.

"Our estimate is at about 3 per cent growth per year, we'd be looking at about 20 years worth of capacity left at the Port of Melbourne," she said.

Dr Parsons said the port had plenty of land space but would rapidly run out of on-water berths for larger container ships.

"The capacity of the Port of Melbourne is limited at the berth, and we have limitations there that require extra development," she said.

"We would be expecting much larger ships be needing to enter Melbourne in the next 10 years."

Greens, farming groups concerned over price gouging

The Opposition, Greens and farming groups also have serious concerns about the potential for port users to be slugged higher fees to use the facility.

Greens leader Greg Barber said the Government was focused on securing a "big number" for the port sale, but has not thought through the consequences.

"The bigger the sale price they get, the more the private operator has to get back," Mr Barber said.

"That comes at the expense of farmers, export managers and anyone who is a port customer."

Mr Pallas said there were safeguards built into the bill to make sure there is no price-gouging of port users.

"They won't be able to essentially price-gouge, they'll have to prove that they're investing in the port, growing the value of the asset and its value to users of the port before any adjustments in price can continue," he said.