MUMBAI/NEW DELHI - The spectacle of the long-feuding billionaire Ambani brothers dancing at a celebration of the 80th anniversary of the birth of their late father this week sent Indian media into a frenzy and reignited speculation the two might again do business together.

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The show of unity by India's richest family came more than a year after Mukesh and Anil Ambani buried the hatchet in a five-year battle that split the business empire inherited from their father, but family watchers were sceptical that the reunion would result in renewed business ties.

"Any deal reached between the two groups will be a hard and ruthless business decision. There is no sentiment involved," said S.P Tulsian, an independent market analyst.

When they ended their feud last year, the brothers also dropped an agreement not to compete on each others' turf. Soon after, Mukesh's Reliance Industries made a dramatic return to telecoms by taking control of the only firm that won wireless broadband licences across India.

That deal makes him a potential rival or partner to Anil's Reliance Communications, which has a $925 million convertible bond due in March and has seen its share price tumble 52 per cent this year in a ferocious cellular market.

Reliance Communications, with about US$6 billion (S$7.8 billion) in debt, has failed in efforts to sell off its tower business but sources have said that US private equity giants Carlyle Group and Blackstone Group are in talks about a possible US$3.5 billion deal for the 95 per cent-owned tower arm.

Market watchers have said Mukesh's nascent broadband business makes a natural tenant for Anil's towers business.

"The only deal on the horizon could be one for Reliance Comm's towers. That is important for RIL's telecom rollout, and it could mean Reliance either becoming a long-term customer for leasing the infrastructure, or picking up a direct stake," said P. Phani Sekhar, a fund manager at Angel Broking.

Mukesh's Reliance Infotel is said to be in talks with firms including Reliance Comm for leasing telecoms towers as it prepares to launch services, but sources have said Mukesh is not looking to buy a stake in his younger brother's tower firm.