Mumbai: Rio Tinto's $15 billion (A$15.63 billion) asset sale proposal seems to be back on track with the sale of the undeveloped Kintyre uranium project in Western Australia to Cameco of Canada and Mitsubishi of Japan for $495 million ($A515 million).

The deal also gives aboriginal landowners the right to secure equity involvement in development of the Kintyre uranium deposit after its sale.

Kintyre is one of the world's biggest undeveloped uranium deposits (80 million pounds of uranium now worth $4.8 billion in its finished form) but its development has been held up by the governments continuing ban on uranium mine developments.

But the aboriginal Martu tribe, the traditional landowners of the mineral belt, will join the new owners to pressure the Labor government to lift the ban.

The sale came five months after Rio Tinto sold interests in two North American mines as part of its plan to pay down its debt.

Rio is also believed to have entered a more advanced stage of a bid to divest its US energy coal business for about $4-5 billion.

Rio is expected to sell a total $10 billion in assets this year, according to chief executive Tom Albanese.

Financial details of the deal struck by the Martu on the sale of Kintyre to Cameco (70 per cent and operator) and Mitsubishi (30 per cent) were not disclosed.

But it is believed to include a mix of equity - possibly up to 20 per cent - and payment of royalties and up-front cash.

Uranium prices have halved in the past year after reaching a record $138 a pound. But the current price of $60 a pound is still a six-fold increase on the $10 a pound price in 2002-03.

The Cameco/Mitsubishi partnership said it would begin working towards a mine development agreement with the Martu following settlement of the Rio deal next month.

It is understood two other miners have taken part in a due diligence process after several companies had expressed interest.

Kintyre is one of the three largest undeveloped uranium deposits in Australia. Rio shelved development plans in the 1990s due to a low uranium price and had tried at least once to sell the asset.

In March, the local Martu traditional landowners complained they had not been properly consulted in the sales process, which required their approval. The Martu yesterday said those concerns had been resolved.

The Kintyre divestment means Rio's only remaining Australian asset for sale is the Northparkes copper-gold mine in NSW, which may be worth about $1 billion.