Microsoft boss Bill Gates remains the world's richest person, according to Forbes magazine's annual rich list.

Gates, whose net worth is estimated to be close to $50bn, tops the list for the 12th year running.

US investor Warren Buffett was second with a personal fortune of $42bn, followed by Mexican industrialist Carlos Slim on $30bn and Ikea founder Ingvar Kamprad on $28bn.

Indian steel magnate Lakshmi Mittal dropped two places to number five with a net worth of 23.5bn.

According to Forbes, the number of billionaires has risen by 15 per cent to 793 over the last year, with a rising number in India, Brazil, Russia and the Middle East.

The combined net worth of the 793 is $2.6 trillion, up 18 per cent since last March.

Luisa Kroll, Forbes magazine: "A billion just isn't what it used to be."

Luisa Kroll, Forbes magazine's associate editor, said: "A billion just isn't what it used to be."

Microsoft co-founder and Seattle Seahawks owner Paul Allen remained in the top ten at number six with $22bn.

French luxury goods mogul Bernard Arnault finished in seventh place with a net worth of $21.5bn, while Saudi Arabian investor Prince Alwaleed Bin Talal Alsaud was eighth with $20bn.

Canadian publishing magnate Kenneth Thomson with $19.6bn and Hutchison Whampoa head Li Ka-shing with $18.8bn complete the Forbes top ten.

Russian oil tycoon and Chelsea owner Roman Abramovich was placed 11th, while Italian prime minister Silvio Berlusconi ranked 37th.

Hind Hariri, 22, daughter of slain Lebanese prime minister Rafik Hariri, is the youngest billionaire on the list with a net worth of $1.4bn.

Gates, 50, who set up Microsoft with Allen in 1975, is also known for his charity work.

The Gates Foundation, established in the name of Gates and his wife Melinda, has spent over $10bn since its inception in 1994, around half of which has been spent on global health issues.