No blasting needed for Melb Port: Pallas

No blasting will ever be needed to open up the Port Phillip Bay heads for shipping, Treasurer Tim Pallas says.

The opposition is concerned larger ships won't be able to access the Port of Melbourne without blasting the bay's heads but Mr Pallas guaranteed that would not happen.

"There will never be the need for the use of explosives in Port Phillip Bay," Mr Pallas told reporters on Thursday.