India’s richest brothers went head-to-head this week in what should be the endgame of the country’s most closely watched legal battle. At stake is at least $17 billion in profits from the subcontinent’s largest natural gas find. But the proceedings will also shed light on the enormous — and growing — power wielded by India’s wealthiest “bollygarchs”.

Mukesh and Anil Ambani, who are worth more than $30 billion (£18 billion) between them, have become infamous for their mutual animosity. Tales of their dislike for each other are legion: they both have apartments in the same building in Mumbai but are said to use separate lifts to avoid meeting each another.

More seriously, such is the siblings’ wealth and influence — between them, they account for more than 5 per cent of India’s annual GDP — some fear that their feuding poses a threat to India’s prosperity.

The Supreme Court hearing in Delhi (which is expected to last for up to three months) also promises to expose the Indian Government’s ad-hoc approach to its hydrocarbon reserves and energy security — a factor, some believe, behind the reluctance of overseas group to bid for exploration rights.

Also at issue will be the cosy relationships that exist between state officials and India's wealthiest families — links that some analysts fear are having a corrosive effect on India's democracy.

The brothers, who are not expected to appear in court, fell out after the death in 2002 of their father, Dhirubhai Ambani, who rose from rags to riches by creating Reliance, an industrial empire that ran from petrochemicals to telecoms, but left no will.

In 2005 the group was split between them under terms hammered out by their mother, Kokilaben, the only person so far able to mediate between them.

Since then, dealings between the pair have sharply deteriorated. Last year the elder, Mukesh, 52, looked to block a potential £35 billion deal that would have allowed Anil, 50, to create a new colossus in the global mobile telephone industry by merging RCom, his mobile phone company, with a South African peer.

Months later, a furious Anil sued Mukesh for more than $1 billion for alleged defamation in an American newspaper.

Their biggest row by far, however, has been over the vast gas deposits discovered off India’s east coat after Reliance, then unified, snapped up the exploration rights of the D6 block of the Krishna-Godavari basin in 1999.

Under the corporate split terms brokered by their mother, Mukesh’s Reliance Industries, agreed to supply gas to Anil’s Reliance Natural Resources at a fixed price of $2.34 per million British thermal units (MBtu) for 17 years.

In 2006 Mukesh said that the deal needed the approval of the Indian Government, which consequently set a higher price, of $4.20 per MBtu, setting into motion an epic legal battle.

The stakes are high: Mukesh is expecting to make $11.5 billion from the gas if it is allowed to sell it at $4.20. If Anil wins the court case, that may tumble to a $5.4 billion loss.

The future of Anil’s Reliance Natural Resources — the company that is to buy the disputed gas — is also hanging in the balance. The company is currently valued at nearly £2 billion. Analysts say that three quarters of its value is likely to be wiped out if Anil loses in the Supreme Court.

For newspaper editors, this is all rather jolly: day-by-day, readers lap up the details of the epic fight between two of India’s richest men.

But many analysts feel that the brothers’ shenanigans — and their complicated relationships with the Government — have affected the way in which foreign investors view India: an important consideration for a country that must raise an estimated $500 billion to upgrade national infrastructure significantly worse than North Korea’s over the next few years.

At home, meanwhile, the Ambanis’ antics have underscored the growing gulf between India’s richest and the rest.

The Asian Development Bank estimates that the country has 50 dollar billionaires. Together they control wealth equivalent to 20 per cent of the country’s annual economic output, and 80 per cent of its stock market capitalisation.

Some fear that the concentration of wealth in so few hands risks destabilising India. The Government has recently been engaged in an austerity drive, with ministers being asked to take economy flights, to show solidarity with the 600 million citizens whose livelihood have been endangered by this year’s poor monsoon. Manmohan Singh, the Prime Minister, has warned the country’s rich elite that their ostentatious spending could trigger “social unrest”.

He is probably not best pleased, then, that Mukesh Ambani is currently building a $2 billion home in South Mumbai — a building said to have been inspired by the Hanging Gardens of Babylon that will be by far the world’s most expensive dwelling place.

Most seriously, perhaps, there are also fears that the emergence of India’s new generation of oligarchs endangers the democratic fabric of the country. These men have made their fortunes through business acumen — and by cultivating the political contacts essential to operate in sectors such as real estate development, power production, mobile telecoms or petrochemicals.

As Saurabh Mukherjea, of Noble Group, an investment bank, said in a recent report: “The concentration of immense wealth, and the power that goes with it, in the hands of a select few [means that] India is fast emerging as a heavyweight plutocracy.”

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