Japanese company Mitsui and Co has agreed to take a 49 per cent interest in Canadian company Uranium One's Australian exploration portfolio, including the Honeymoon uranium mine in South Australia.

Uranium One said on Thursday Mitsui would acquire a 49 per cent interest in the Honeymoon project and the Gould's Dam and Billeroo projects, as well as prospective tenements on the Stuart Shelf and Eyre Peninsula.

The minimum cash commitment from Mitsui will be about $104 million for its share of Uranium One Australia's business.

Uranium One said the majority of the funds would be used to advance the development of the Honeymoon project through to commercial production.

Uranium One' executive vice-president, Australia and Asia, Greg Cochran, said the agreement meant final planning of the construction and operation of the project would now take place, with site development resuming early next year and a revised production date of 2010.

"The partnership strategy was undertaken to ensure the development of the Honeymoon project and enhance the value and growth prospects of our Australian business," Mr Cochran said in a statement.

"We are naturally delighted to welcome Mitsui as our partner in this venture.

"Quite apart from the positive implications for Uranium One and Honeymoon, this agreement is a huge vote of confidence in the Australian mining industry and the South Australian uranium industry."

The deal was conditional upon both companies obtaining regulatory approvals, including Australian government regulatory approvals, which were expected by the end of the year.

"We should soon be able to proceed with full confidence and build Honeymoon, as well as develop our other South Australian prospects that complement our project pipeline," Mr Cochran said.

SA Premier Mike Rann welcomed the agreement.

"The decision by an overseas investor to commit millions of dollars to develop this mine amid the current global economic uncertainty highlights the confidence resource companies have in SA," Mr Rann said in a statement.

The government said the Honeymoon mine would be capable of producing 400 tonnes of uranium oxide a year, with an expected mine life of six to seven years. – Associated Press