Infrastructure Australia (IA) says building a second Bass Strait interconnector linking Tasmania to the mainland is a national priority.

The notion of building a new Basslink undersea cable gained support in the wake of the existing cable’s failure, and is considered crucial to Tasmania becoming the ‘Battery of the Nation’.

Having the proposal on IA’s national priority initiative list is a big mark in its favour.

Infrastructure Australia was set up to independently assess projects and initiatives for “nationally significant infrastructure investments Australia needs”.

“At this stage it looks like an interesting initiative and we look forward to working with our colleagues in Tasmania to support their development of the business case,” IA chief Phillip Davies said.

A business case study of the second Basslink cable plan - expected to cost up to $20 million in state and federal funds – has been announced.

A study into a similar proposal by Dr John Tamblyn in 2016 said a second cable would only be commercially viable in a handful of scenarios.

Energy analyst Marc White says there estimates that the cost of the cable would be between $600 million and $1.2 billion, but those need to be tested.

“Our understanding is the business case really hasn't been made yet for the investment, although it is always a good idea to be ready in case that business case changes,” he told reporters.

The Tasmanian Government has welcomed IA’s support for the plan.