The Australian government is in talks with the UK and United States on rolling out a fleet of nuclear-power submarines to replace the ageing Collins class boats, as part of the AUKUS agreement.

But no decision has been made on using the British Astute class model or the US Virginia class.

An 18-month consultation period on the technology is due to wrap up in March.

Anne-Marie Trevelyan told a forum in Adelaide on Friday the British government was committed to seeing the project through for the long term.

"I am personally committed to ensuring that the whole ecosystem which we have in the UK to build, upskill and maintain our own UK submarine enterprise will be right alongside you ... as you start on this complex and technically demanding defence commitment," she said.

"It's going to span everything from construction to creating a nuclear engineering skills ecosystem to the training of your sailors to the through-life maintenance support and decommissioning of your AUKUS submarines."

Defence Minister Richard Marles, who is in the UK to inspect submarine-building facilities, said agreement had been reached on Australian submariners training and serving on the UK fleet.

Trade Minister Don Farrell, who met with Ms Trevelyan in Adelaide, said defence had been on the agenda as well as space, hi-tech and agriculture industries.

"Our economic and trade relationship will continue to grow from strength to strength with the finalisation of the Australia-United Kingdom free trade agreement," he said.

Australia is due to pass the FTA legislation through parliament by the end of the year, while the international trade secretary will introduce the bill into the British parliament on Tuesday, with the hopes of it coming into force early next year.

Senator Farrell also welcomed the UK's progress towards its accession to the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (C-TPP).

Australian Associated Press