Winning thousands of dollars could really be the start of something big, especially for an economist, but Muhammad Yunus is not interested in personal fortune. He decided that his share of the $1.4 million Nobel Peace Prize that he won in 2006 would be used to help others. Part of it was used to create a company producing low-cost, high-nutrition food for the world's poor and the rest went towards founding an eye hospital in Bangladesh.

The investment decisions were characteristic of a man who says that he can envisage a time when people visit “poverty museums”. Born in what was British India in 1940, he won the Nobel Prize for his work on micro-finance, the lending of tiny sums to very poor people to help them to transform their lives. His first loan of $27 to 42 village women came out of his own pocket. Each made a profit of about 2 cents on the loan, enough to start a new industry.

Some of the world's most astute investors are buying into Dr Yunus's ideas. Sequioa, the investor behind Google, recently took a stake in SKS, India's largest microfinancier.

With estimates suggesting that demand for microcredit stands at about $250 billion (£167 billion), ten times the amount lent so far, Citigroup and HSBC plan to make it a mainstream business. As Time magazine put it: “the pinstripes are chasing the poor”. Meanwhile, Grameen Bank, Dr Yunus's microfinancier, has diversified into sectors ranging from software to knitware.

There are fears, however, that if microfinance proves to be too good a business, its original social mission — better conditions for the world's poorest — will be crowded out by the need for profit. In South Africa, experts say that loans are being misused to buy television sets and other luxuries. In Bolivia there are fears that microfinance will go the way of pawnbroking, a pariah among financial services.

Such fears appear to be at the root of Dr Yunus's dispute with Telenor, the Norwegian group, in partnership with which he founded Grameenphone in 1996. Dr Yunus believes that Grameenphone, Bangladesh's largest mobile operator, should be controlled by his non-profit group, Grameen Telecom, which owns 38 per cent of it, and run for the benefit of Bangladesh's impoverished. Telenor executives admit that this was the original intention, but say that now they have thought better of it.

Few are surprised by Telenor's change of heart. Grameenphone's revenues were up 11 per cent in the third quarter and Western operators facing stagnant home markets are desperate to tap into such growth. For the time being, it seems, the Telenor pinstripes are not ready to stop pursuing Bangladesh's poor.

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