WHEN Indian officials arrive in the heart of the United States' oil capital, Houston, next week for the country's largest ever auction of hydrocarbons — the gas-rich seabed under the Bay of Bengal — they hope interest would be high. It will be, but perhaps not because of the supposed treasure beneath the waves.

Instead, what has transfixed investors inside, and outside, India is a bruising public spat between two of the richest men in the world, Mukesh Ambani and his younger brother Anil.

At the heart of the row between Asia's richest siblings is the cost of gas from a huge hydrocarbon field in the Krishna-Godavari basin. Over the last few weeks, Anil Ambani, whose net worth exceeds $10bn, has gone public attacking the oil minister, an old family friend, for siding with his elder brother and writing to the prime minister with a catalogue of complaints over how his company has been treated.

Last month, in a televised address to shareholders, the younger Ambani said his older brother had “tried every trick in the book, and apparently several outside the book, to back out of its solemn, legal and contractual obligations”.

Not only will the rancour cast a shadow over the Indian hydrocarbon roadshow next week, it comes just days before a hearing by the country's supreme court on the dispute between the estranged siblings.

On Tuesday, Anil Ambani raised the stakes again with a series of stinging advertisements on the front pages of the Indian newspapers claiming that the government's stand in the row may lead to a 50 per cent rise in power bills. The adverts were headlined “Is this in the public or national interest?”

Mukesh Ambani shot back with a statement claiming Anil was “indulging in an orchestrated campaign intended to bring into public debate and prejudge the issues that are pending adjudication before the honourable courts”.

Both have been jousting since their mother divided their inheritance, Reliance, India's biggest conglomerate, between them in 2005. Their father, Reliance's founder Dhirubhai, died without leaving a will in 2002.

The division of the company left Mukesh with lucrative petrochemical, oil and gas, refining and manufacturing units. Anil got a smaller portion in the booming fields of telecoms, financial services and power generation.

The brothers, who live on different levels of the same Mumbai tower block but do not talk to each other, had agreed not to compete against each other.

However, their rivalry has led them to accumulate fabulous wealth amid accusations that each is out to undo the other. Some of this appears frivolous. When the older Ambani brought his wife a jet for $52m, the younger brother responded with a gift of a luxury yacht worth $80m for his wife.

In business, however, the family feud is taking a serious turn. Last year Mukesh, ranked by Forbes magazine as the seventh richest man in the world with a fortune of $20bn, blocked a proposed $40bn reverse takeover of the South African mobile group MTN by Anil's Reliance Communications.

But their biggest row now centres on gas. Under the terms of their split, Mukesh's main vehicle Reliance Industries was to supply gas from the vast field in the Bay of Bengal's “D6” block to the younger brother's Reliance Natural Resources at a fixed price of $2.34 per million British thermal units (MBtu) for 17 years.

However, Reliance Industries claimed that the price agreed had to be sanctioned by the government. In 2007, ministers set a different price — almost twice the original — of $4.20 per MBtu. Officials said this reflected higher oil prices, market demand and agricultural inputs such as fertilisers, which are crucial for millions of poor farmers in India.

Undeterred by the state, Anil Ambani took the case to court. In June judges in Mumbai upheld the family's original deal and the lower price.

— The Guardian, London