Talks between Aditya Birla Group, which owns a 47 percent stake in Idea, and South Africa's MTN are at an early stage and may not result in a transaction, Bloomberg reported the sources as saying. The sources declined to be identified because the information is private.
Malaysia's Axiata Group Bhd owns a 19 percent stake in Idea.
Idea's market capitalisation is about $5 billion and Aditya Birla Group's stake is valued at about $2.35 billion, according to data compiled by Bloomberg.
Any deal with MTN would likely involve a mix of cash and shares, one of the sources told the agency.
A spokeswoman for the Aditya Birla Group in Mumbai denied that the firm was in talks to sell the stake, while MTN declined to comment, Bloomberg reported.
Axiata, Malaysia's second-largest mobile phone operator, reported a quarterly loss in February after writing down its investment in India and warned of more challenges ahead as competition intensifies.