The world's richest man, Mexican telecommunications tycoon Carlos Slim, has bought the Duke-Semans Mansion in New York for $44 million from a former Soviet immigrant, the Luxist site said.

Former cab driver Tamir Sapir, who made his fortune trading fertilizer, listed the seven-story Beaux Arts townhouse, the only private mansion left on Fifth Avenue, for $50 million but Slim managed to knock $6 million off the asking price.

Sapir bought the mansion from relatives of U.S. heiress Doris Duke for $40 million in 2006.

"The 20,000-square-foot mansion, built in 1901, currently has a doctor's office in the basement, a five-story main residence, a penthouse duplex on top, 12 bedrooms, 14 bathrooms, and 11 wood-burning fireplaces," Luxus said.

Slim, who co-owns mobile service provider AmericaMovil, overtook American tycoons Bill Gates and Warren Buffett to become the wealthiest person on earth, according to the 2010 Forbes list of the World's Billionaires.

His wealth is estimated at $53.5 billion, up $18.5 billion in a year, which some media estimates say accounts for 8% of Mexico's GDP.

MOSCOW, July 29 (RIA Novosti)