Melbourne's second major container port should be built near Werribee, the Andrews government's infrastructure adviser says, but not for another 40 years or so.

Infrastructure Victoria has advised the government that Bay West, somewhere between Werribee and Point Wilson, is the right choice for a future port, once container traffic outgrows capacity at the Port of Melbourne.

Australia and New Zealand each announced on Saturday the start of free trade agreement negotiations with the Pacific Alliance trade bloc. Credit:Jessica Shapiro

The port's container terminal would be built offshore – a four-kilometre-long industrial island connected with the mainland via a 1½-kilometre road and rail bridge that would radically reshape Port Phillip Bay.

New road and rail links would also be built across Melbourne Water's vast Western Treatment Plant, which is also a protected site for birdlife.