Talks between the Victorian Government and Opposition over the privatisation of the Port of Melbourne have stalled, amid fears the negotiations could fall foul of a future anti-corruption investigation.

Legislation to sell the port's long-term lease has been delayed in the Upper House and the Government had hoped to secure the Coalition's support to pass it when Parliament returned next month.

But the Opposition said sweeping new powers being given to anti-corruption body IBAC could make the negotiations the subject of a malicious complaint in the future.

Victorian Opposition Leader Matthew Guy said he received a briefing this morning that provisions to investigate "misconduct in public office" could apply to political negotiations.

"[The changes] say very, very clearly that political horse-trading, political discussions, could be the subject of future IBAC investigation," he said.

"The Government is very keen to tell me that this is not the case in relation to this bill, but they can give no guarantee.

"And as a consequence I want everything to be in writing, every piece of offer, discussion, negotiation with the Government must now be in writing."

Mr Guy said all the conversations he has had with the Government about the port sale have been above board, but he was concerned any face-to-face conversations about the Port sale could be used against him maliciously in the future.

The Government's IBAC legislation is so broad that every discussion over legislation between minor parties, between lobbyists, between departments, journalists, everyone - these issues will now be subject to IBAC investigation," he said.

"I don't think that's been properly thought out by the Government."

The Government needs the support of the Coalition, or the Greens and crossbenchers, to get the legislation to sell the Port's lease through Parliament.

It could also start the process of privatising the asset, worth around $7 billion, without the Parliament's support.