Mexican tycoon Carlos Slim is the world's richest person, knocking Microsoft founder Bill Gates into second spot, as the wealth of the world's billionaires grew by 50 per cent over the last year.

Forbes magazine reports it's only the second time since 1995 that Gates has lost the crown.

Slim's net worth has been pegged at 53.5 billion dollars, whereas Gates has a fortune of 53 billion dollars. Investor Warren Buffett came in at number three with 47 billion dollars.

Slim, a telecommunications magnate, made his fortune after buying Mexico's national telephone company on the cheap in 1990, The Times reported.

An engineer by training, he now controls more than 200 businesses, ranging from mining and construction groups to hotels and cigarette-makers.

There are now 1011 billionaires, compared with 793 last year and 1125 in 2008. (ANI)