Despite being the world's fourth richest man, Mr Kamprad said he was very fond of his Japanese-designed Poäng chair and saw no reason why he should replace it. "I've had it for 32 years. My wife thinks I should get another one because in the meantime the material has got dirty," he said. "But technically it's as good as new."

Mr Kamprad told the Swiss magazine Bilanz that all his furniture came from IKEA - apart from an "old chair and a beautiful standing clock" inherited from his mother. Earlier this year Fortune magazine estimated Kamprad's wealth at $28bn (£14bn), behind only Bill Gates, the US investor Warren Buffett and the Mexican industrialist Carlos Slim.

The 80-year-old Swede lives in Epalinges, above Lake Geneva, and is Switzerland's richest resident, according to Bilanz. Yesterday, however, Mr Kamprad said his personal fortune had been exaggerated. "It doesn't have anything to do with reality," he grumbled. IKEA was owned by a charitable trust, he said.

Mr Kamprad started from his garden shed, selling watches, pens and Christmas cards. He stumbled on the flat-pack furniture idea in the 1950s when an employee took the legs off a table to fit it into a customer's car.

Nowadays, IKEA is the world's biggest furniture retailer, with 237 stores in some 35 countries and territories and a forecast 2006 turnover of €17.7bn (about £12bn), still basing its business on that inexpensive self-assembly furniture.

But Mr Kamprad does not believe one of his three sons - all of whom work for IKEA and take three-year stints as chair of the executive board - will go on to take charge of the business. "The problem is being head of a business is hard work. You can keep it up for eight to 10 years, at most. That's why I believe - or I should say, I hope - that none of my sons goes on to be the boss."

Mr Kamprad visits his stores 25 to 30 times every year, in different parts of the world. He still travels on discount tickets. Recently German security guards refused to let him in to collect an award for entrepreneur of the year after he arrived by bus.

"It's always fun," he said of his IKEA visits. "And work should always be fun for all colleagues. We all only have one life. A third of life is work. Without desire and fun, work becomes hell."