INDIA'S largest private company has committed to spending almost $13 million to explore for uranium in South Australia and the Northern Territory.

Uranium Exploration Australia (UXA) said yesterday it had signed an agreement with Reliance Industries to explore across eight exploration tenements.

Reliance is the largest private sector company in India and is owned by India's, and perhaps the world's, richest family -- the Ambanis.

The Ambani brothers, Anil and Mukesh, are estimated to be worth close to $US100 billion according to The Wall Street Journal.

Reliance has interest in textiles, retail, oil and gas exploration and production, petroleum refining, petrochemicals and marketing with annual revenues of more than $US27 billion.

Under the deal with UXA, Reliance will earn a 49 per cent interest in return for $3.45 million in cash, and contribution to further exploration.

The tenements involved include four near the Olympic Dam mine in northern SA.

"UXA and Reliance intend to pursue an aggressive exploration program on these tenements over the next three years with an estimated outlay of up to $19.4 million," UXA said in a statement.

UXA managing director Patrick Mutz said the relationship started at a mining conference in Adelaide in March.

"We are very excited to have a company of the calibre and status of Reliance as UXA's second joint venture partner, after the May 2007 joint venture with Newcrest Operations.

"Reliance's entry into the uranium exploration industry in Australia underscores the strong fundamentals of the uranium market going forward, with medium and long-term pressures on the price of uranium due to supply limitations," Mr Mutz said.