It has been a good year for billionaires, according to Forbes Magazine's global rich list, with the world's wealthiest increasing their collective worth by some $300 billion (£156bn).

The economic climate was especially kind to those with fortunes linked to the commodity markets. Boosted by soaring steel prices, the fastest-growing fortune belongs to the Indian-born British steel tycoon, Lakshmi Mittal, who is No 3 on the list, published today, with an estimated net worth of $25 billion.

Mr Mittal saw his net worth surge from an estimated $6.2 billion last year and his ranking jump from 62nd on last year's Forbes list.

"Commodities like oil and steel played a big part in the increasing fortunes," Forbes said.

Mr Mittal began his career in the early 1970s in his father’s small steel firm in the north of India. The businessman, whose interests have since been linked to New Labour, recently formed Mittal Steel through the merger of Ispat International and LNM Holdings.

He is awaiting regulatory clearance to take over ISG, of America, after which he will control the largest steel group in the world.

The American software tycoon, Bill Gates, who founded Microsoft, remains at the top of the ranking for the 11th consecutive year, with an estimated personal fortune of $46.6 billion. But the gap narrowed between Mr Gates and the second-placed billionaire, the veteran investor Warren Buffett.

Mr Buffett, who is known by investors as the "Sage of Omaha" for his skills in reading the markets, is worth an estimated $44 billion.

The Mexican businessman Carlos Slim Helu joined the top ten as the fourth wealthiest individual, worth some $23.8 billion thanks to a $10 billion increase in his telecom fortune, Forbes said.

The second highest ranked British-based billionaire is Roman Abramovich, the Russian oil and aluminium magnate who owns Chelsea football club and spends most of his time at his London and Sussex homes. Mr Abramovich is reckoned by Forbes to be worth $13.3 billion, ranking him 21st overall.

Retail entrepreneur Philip Green and his wife Cristina, with $6.8 billion at 68th on the list, are the leading British-born billionaires - although they are registered as living in Monte Carlo.

Overall, the number of billionaires grew to 691 in the 2005 edition of the list, from 587 a year earlier, and their net worth jumped to $2,200 billion from $1,900 billion.

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