Billionaire U.S. investor Warren Buffett has canceled a trip next week to attend a plant opening ceremony for Tungaloy Corp. in Fukushima Prefecture following the nation's strongest earthquake.

Buffett, chairman of Berkshire Hathaway Inc., was originally scheduled to arrive in Fukushima on March 21 and attend the ceremony the next day, Tungaloy said in an e-mailed statement. Buffett didn't immediately respond to an e-mail sent Sunday to his assistant, Debbie Bosanek.

The 9.0-magnitude quake and subsequent tsunami on March 11 may have killed 10,000 in Miyagi Prefecture alone, according to the police. Radiation levels around a nuclear power plant in Fukushima Prefecture run by Tokyo Electric Power Co. rose after cooling systems at a second reactor failed, heightening concerns about another partial meltdown following explosions over the weekend and on Monday.

Tungaloy, owned by Iscar Metalworking Cos., is Berkshire's largest acquisition of a non-U.S. firm.

The 80-year-old billionaire investor is still scheduled to visit TaeguTec Ltd., a manufacturer in Daegu, South Korea, on March 21, said Yang Sun Young, a spokeswoman at the Korean firm.

Omaha, Neb.-based Berkshire has been transformed by Buffett over four decades from a failing textile maker to a $200 billion seller of insurance, electrical power and consumer goods. Berkshire doesn't pay a dividend or buy back shares, leaving Buffett with the task of investing the firm's earnings in stocks, bonds and takeovers.

Buffett, also Berkshire's chief executive officer and biggest shareholder, paid $4 billion for 80 percent of Iscar in 2006. In 2009, he injected about $2.6 billion into Swiss Reinsurance Co., the second-biggest seller of backstop coverage for insurers.

His net worth was estimated at $50 billion by Forbes magazine, which this month ranked him as the world's third-richest person, after Carlos Slim and Bill Gates.