Mexican telecom billionaire Carlos Slim has overtaken Microsoft founder Bill Gates as the world's wealthiest man with riches of $59 billion, Fortune magazine said on Monday.

Fortune, which tracks the performance of the world's top companies, said Slim has increased his net worth by $12 billion so far this year based on the market value of his companies listed on stock exchanges.

In an online profile of Slim, 67, Fortune said he had a fortune of $59 billion based on the value of his public holdings at the end of July.

Gates, the Microsoft founder and perennial No. 1, had a net worth estimated to be at least $58 billion, the magazine said.

Slim, the son of a Lebanese immigrant, owns Latin America's largest cell phone company America Movil.

Fortune said Slim's companies, ranging from a restaurant chain to a bank, made up a third of the Mexican stock market and his family's holdings represented more than 5 percent of Mexico's gross domestic product last year.

In July, a respected Mexican financial journalist announced that Slim had overtaken Gates as the world's richest man but the magnate said he did not care.

It's water off a duck's back to me, the cigar-smoking Slim told foreign correspondents last week. I don't know if I'm No. 1, No. 20, or No. 2,000. It doesn't matter.

Gates and billionaire U.S. investor Warren Buffett, who was the second-richest person in the world until Slim overtook him this year, have been giving more of their money to charity in recent years.

Slim also backs philanthropic causes and last week announced a $300 million plan to build 100 schools in Mexico, but says he does more good by creating wealth and jobs through his own companies.

Mexico Bill Gates Warren buffett Microsoft