Man in the news: Anil Ambani

Anil Ambani, the Indian industrialist, was on a family holiday in a game park in South Africa earlier this month when the news came. Takeover talks had collapsed between rival billionaire entrepreneur Sunil Mittal, chairman of India 's biggest mobile carrier Bharti Airtel, and MTN, the South African wireless operator. Mr Ambani promptly switched from passively viewing the big game to hunting - going after one of the biggest emerging markets telecoms groups.

Last week, his mobile phone company, Reliance Communications, engaged MTN in exclusive talks for an audacious reverse takeover that would put him at the helm of a group with 115m subscribers across Africa, the Middle East and India . In some estimates the deal could be worth $20bn (10 bn pounds, euro 13bn) - the largest overseas takeover tried by an Indian company.

People who know Mr Ambani, estimated by Forbes as the world's sixth richest man with a net worth of about $42bn, say the deal is typical of his aggressive style. "He has an absolute killer instinct, he is competitive as hell," says one industry insider from a rival company in India .

The deal, if he can pull it off, would offer a dramatic validation of his business skills, allaying any residual insecurities from the bitter public succession battle with his elder brother, Mukesh, after his father, Dhirubhai, died without a will in 2002. Dhirubhai started out as a petrol pump attendant and became legendary as the founder of one of India 's biggest private companies, Reliance Industries, an oil and petrochemicals group. He remains revered among Indian retail investors for his Midas touch, an Indian Warren Buffett.

Mr Ambani was born in Bombay in June 1959. He earned a bachelor of science degree from the University of Bombay and an MBA from the Wharton School of the University of Pennsylvania. He returned to India to join the family company and became co-chief executive officer in 1983, when he began to earn a reputation for financial innovation. Under their father, Mukesh was charged with project management while Anil took care of marketing and fundraising.

The eventual succession battle took seven months to resolve, when their mother brokered a deal. As part of the settlement in 2005, Anil received about 30 per cent of Reliance's assets, principally its telecoms arm, now known as Reliance Communications, and its financial services and energy divisions.

Anil revered his father - he still starts press briefings with a floor-to-ceiling slide of Dhirubhai. "This is the first time he's on his own, there's no father or brother around to help. He's very driven to prove things to himself rather than anything else," says one person who has worked with both brothers.

Since 2005 he has pursued bold initiatives. These include India 's biggest initial public offering, the $3bn listing of Reliance Power, in January to a $1bn deal, announced this month, to make films with illustrious Hollywood groups from George Clooney's Smokehouse Productions to Brad Pitt's Plan B Entertainment. When he took over the group in 2005, its market capitalisation was about $5bn. Now it is $75bn.

The Bollywood connection is not just business. He is at ease in the vibrant social set and close friends with the family of Amitabh Bachchan, the Bollywood superstar. He is also married to Tina Munim, a former Bollywood actress, with whom he has two children.

The family lives in south Mumbai in one part of an apartment block he shares with Mukesh, (the latter is, however, building a $2bn, 27-storey home, which could erase fears of ever invading each other's personal space). The two estranged brothers work different hours, so rarely meet in the elevator. Anil arrives at work by helicopter at his business park by 9.30am and returns about 12 hours later. Mukesh starts at midday and finishes by midnight.

Anil is a devout Hindu and never drinks or smokes. Although described as "a health freak", he likes his food spicy hot, so much so that one person remarked he has food with his chilli, not vice versa. After being teased about his weight, he took up marathon running and often runs 100km a week. He has become a familiar sight in his Wharton T-shirt running a 15 km loop along Marine Drive, the half-moon boulevard that defines south Mumbai's seafront. "He runs on a treadmill at a speed of some 14km per hour and on the streets of Bombay at a speed of 12km per hour, so frankly, he's a man in a hurry," says the person who knows the brothers.

He is not immune to the allure of fast cars. He was a fan of Porches and Lamborghinis, but today prefers his Range Rover, more practical for Mumbai's pot-holed roads. He retains a love of driving and asks his chauffeur to move aside and sit in the passenger seat whenever he has time to take the wheel.

For all the blistering corporate activity, Anil's critics argue that he has yet to prove he can build businesses as well as his brother Mukesh, who some see as a genius at executing large projects, compared with Anil who is better known as a gifted and articulate presenter. "He has an unbelievable grasp of facts and numbers, he's something of a financial genius and a genius at understanding capital markets", said one executive from a rival company. "What he is lacking is the ability to put strong people around him whom he will give rope to, so as a result, he hasn't attracted as high quality a team around him as his brother has."

Anil's competitors also charge him with being too close to regulators, with his businesses benefting from regulatory loopholes, such as in building his mobile network. He has strong political ties and was elected in 2004 as an independent member of the Rajya Sabha, Upper House, in June 2004. He resigned in 2006.

Moreover, not everything has gone right. Reliance Power, after its blockbuster IPO in January, plummeted 17 per cent on its trading debut the following month amid the credit crisis. Worried that the fall could damage Reliance's reputation for always rewarding shareholders, Mr Ambani compensated them by issuing them with free shares.

The IPO also revealed continued tensions with his brother. Some joked they were competing to top the Forbes billionaires list. Mukesh finished one notch higher, at number five with $43bn. This could change if Anil secures MTN (he would be the first brother to make a big overseas acquisition). So far this is sibling rivalry that has proved constructive and productive; but Mr Ambani still needs to prove he can catch his hunted quarry.