(Bloomberg) -- Indian billionaire Mukesh Ambani’s Reliance Industries Ltd. is considering selling as much as 25 percent of its refinery business in a deal that could fetch at least $10 billion, people with knowledge of the matter said.

Reliance is sounding out potential investors including state-owned Saudi Arabian Oil Co. and Abu Dhabi National Oil Co. to gauge their interest, according to the people, who asked not to be identified because the information is private. Aramco has also been considering investing in a new Indian refinery that Reliance is planning to build, the people said.

Discussions are at an early stage, and valuation could be a hurdle to any agreement on a stake sale, the people said. Aramco has been weighing various deals that would increase its exposure to Reliance’s refining operations, though it hasn’t made a decision on what form any eventual investment would take, the people said.

Middle Eastern oil giants like Aramco and Adnoc have been expanding into downstream operations as they seek to move from being pure producers to becoming more integrated energy companies. Reliance’s debt pile has risen over the past few years, as the Indian conglomerate poured money into new sectors such as telecommunications, and stood at $32 billion at the end of December, data compiled by Bloomberg show.

Reliance has been considering building a third plant at its giant Jamnagar complex in western India’s Gujarat state, Bloomberg News reported in November. The proposed facility would be able to process as much as 30 million tons of crude per year, which would boost its oil-refining capacity by about half, people with knowledge of the matter said at the time.

“Our company evaluates various opportunities on an ongoing basis,” Reliance said in an emailed statement, declining to comment further.

Aramco declined to comment in an emailed statement. A representative for Adnoc didn’t have an immediate comment. The Times of India reported earlier Wednesday that Aramco is in talks to buy a stake in Reliance’s refinery and petrochemicals business, citing unidentified people.

©2019 Bloomberg L.P.