WHAT kind of man travels halfway round the world to sabotage the biggest deal of your career, publicly humiliates your mother and then threatens you with legal action? For supporters of Anil Ambani, the second richest man in India, the answer is “your older brother”.

India is no stranger to sibling rivalry, but the feud between Anil and Mukesh Ambani, the world’s richest brothers - their combined fortune is $85 billion (£42 billion) - has enthralled the country’s business community.

Indian ministers, who believed the rift was settled when the Reliance family business was divided between the brothers in 2006, were alarmed last week when Mukesh Ambani, the older and richer brother, reopened hostilities in an attempt to thwart younger brother Anil’s proposed $50 billion takeover of the South African mobile-phone giant MTN.

Mukesh published a letter to MTN and his younger brother, warning that the deal would be in breach of the family agreement that divided the Reliance empire and would be challenged in court.

The letter was released while Mukesh was holidaying in Botswana amid rumours that he had been lobbying to stop the deal. According to Anil’s supporters, Mukesh’s backers were working behind the scenes to persuade American financiers not to lend Anil the $7 billion he needs to complete the deal.

A spokesman for Mukesh denied the allegations, saying his holiday in Botswana was a coincidence, and that he had not lobbied anyone over the deal. He had merely written a letter stating that the deal would be in breach of a family agreement, which he claims gives him right of first refusal if Anil sells his shares in any of the Reliance companies he controls.

The row threatens to rewrite several scenes in the Ambani-Reliance script, and offers a natural sequel to the Bollywood blockbuster Guru, which was based on the life of their father, Dhirubhai, who began his working life in a petrol station and went on to build Reliance into India’s biggest company.

Until now, the story has cast Mukesh as the steady, hard-working son who built the world’s largest petroleum refinery at Jamnagar. When the Reliance empire was divided, his share was estimated to be worth at least three times the value of the companies handed to Anil.

Mukesh’s supporters said this was only fair because of the two, he was the recognised business leader. They said Anil was a playboy who associated with disreputable politicians, appeared in gossip columns with film stars and had yet to prove himself as a business leader in his own right.

When Anil failed to win the contract to build a new international airport for Delhi, his critics seized on it as evidence that he had alienated ministers by associating with their opponents, and that his lifestyle was undermining his business.

Today, Anil seems set to reverse the roles. Since 2006, his personal wealth has increased to within $1 billion of his brother’s $43 billion, and will leapfrog him if the MTN deal goes through.

He has expanded his media interests with Reliance Big Entertainment, signing a series of production deals with Tom Hanks, Brad Pitt, George Clooney and Nicolas Cage, and is about to fund Steven Spielberg’s relaunch of Dreamworks. Last week he struck a deal to fund new ventures with Bollywood’s biggest stars, Amitabh Bachchan, his son Abhishek and daughter-in-law Aishwarya Rai.

While Anil backed away from the limelight, Mukesh stepped into it. There has been a stream of stories about Mukesh’s lavish lifestyle - from buying his wife a Boeing jet as a birthday present to building what is believed to be the world’s most expensive “house” overlooking the sea in Mumbai – the 27-storey apartment block called Antilia, which will cost an estimated $1 billion and boast its own cinema, pool and helicopter pad.

Anil’s supporters contrast Mukesh’s conspicuous spending with their man’s “miserly and spartan” lifestyle - he stays in standard single hotel rooms on business trips, and runs 18 kilometres a day, six days a week.

Anil’s supporters say Mukesh has been foolish in underestimating his strengths. The brothers had been given specific roles by their father. Mukesh was encouraged to take on big infrastructure projects, and create new businesses. Anil was sent to Harvard to master finance and become the public face of the firm - building relationships with politicians and bankers.

Family friends said the split was a tragedy because the brothers had complemented each other’s strengths and compensated for each other’s weaknesses. Today their communication is mainly through lawyers and PR firms, and is restricted to necessary pleasantries at family breakfasts with their mother, Kokilaben.

Anil is said to have a special bond with the matriarch, which some believe led her to call in top Indian banking friends to divide the family empire when the rift between Mukesh and Anil became public in 2004.

Now she is caught in the middle again. She helped Anil host a dinner at Christie’s this month, and sat next to MTN chairman Phuthuma Nhleko - which was widely interpreted as her blessing for Anil’s deal.

Mukesh’s intervention in the MTN deal was seen by some as a public humiliation for Kokilaben - strictly taboo in Indian culture, where mothers are revered. His friends angrily deny there was any such intention.

There are a number of theories about why Mukesh has attempted to intervene in the MTN deal. One is that he did so after his friend Sunil Mittal, the boss of Anil’s mobile-phone rival Airtel, lost out in his own bid to buy MTN. Mukesh depends on Airtel for his communications.

Another has it that Mukesh has created a public row to use as leverage in a dispute over gas supplies to Anil’s power business. When the empire was split, Mukesh got the gas and oil exploration, production and refining interests, while Anil got the power generation and distribution. A deal was struck that Mukesh’s energy firms would guarantee gas at a fixed price to Anil. Mukesh is understood to want to revisit the agreement.

Friends say the true answer is more primal. They were both raised by their father to be alpha leaders, and each wants to be No 1. “Mukesh is the richest man in India, and he doesn’t want to be overtaken by the younger brother everyone said was too flamboyant to succeed. Anil not only wants to overtake his brother, he wants to be the richest man in the world, and I think he will be,” said one family friend.

The MTN deal will set Anil on his way. Under the proposal, MTN’s 45m subscribers in India, Sri Lanka and Uganda would be combined with MTN’s 68m customers throughout Africa and the Middle East to create the world’s fourth-biggest mobile-phone operator.

Anil has offered cash and Reliance Communications shares valued at $45 billion for a 35% stake in MTN, but he will also invest a further $10 billion in cash to make him the undisputed owner with a 50% holding. MTN would take control of Anil’s stake in Reliance Communications, but he would remain in control through his effective acquisition of MTN.

“This will not be a merger of equals. It’s more like Lakshmi Mittal’s deal to buy [rival steel group] Arcelor, and it will make Anil the richest Indian in India, and possibly the world,” said a source close to the Ambanis.

“The new company will be worth more than $90 billion and its earnings will be significantly higher than Mukesh’s – $10 billion compared with $7 billion. It will take Anil’s fortune to about $55 billion. It’s possible that Lakshmi Mittal has one or two more, but Anil will be the richest man in the world in two years.”

The Ambani saga look likely to keep Bollywood busy for some time to come.

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