Australia's nuclear submarines won't be ready until the 2040s, leaving the nation vulnerable as our existing submarines retire beginning in 2038.

Defence Minister Richard Marles said he wants to speed up the process but getting a nuclear sub by 2030 is 'optimistic in the extreme'.

In an ABC Radio interview on Tuesday morning he reiterated that Australia's first nuclear submarine using British or American technology is not expected to hit the water until the 2040s.

'The truth of where the former government left us at the time of the election is that they were looking at a new nuclear submarine in the 2040s. That's where they were at,' he said.

Asked if that timeframe could be brought forward to as early as 2030, Mr Marles said that would be 'optimistic in the extreme'.

'We will be looking at every option available to try and bring that time forward. I think bringing it forward to eight years from now would be extremely optimistic.'

The Coalition planned to extend the life of Australia's six Collins class submarines but even with the extension the first one is due to retire in 2038.

Former Defence Minister Peter Dutton earlier this month revealed Defence was investigating buying two Virginia-class nuclear-powered submarines from the US by 2030.

The arrival of the submarines would be at least 10 years ahead of schedule, compared with being built in Australia.

Mr Marles said he was open-minded about options to bridge the gap.

'We need to look at how we bridge the gap. That's all I can say. And my mind is open about how we do that,' he said earlier this month.

Australia announced plans to acquire six nuclear-powered submarines under the AUKUS agreements with the US and UK last year.

The move meant dumping a $90 billion contract for conventional diesel-powered submarines by French company Naval Group.

Anthony Albanese will meet French President Emmanuel Macron this week to repair relations after the announcement infuriated the French government.