Billionaire investor Warren Buffett believes Japan's devastating earthquake is the kind of extraordinary event that creates a buying opportunity for shares in Japanese companies.

Japan, the world's third-largest economy, has been battling to bring an overheating nuclear plant under control after it was battered by the March 11 earthquake and tsunami that rattled global markets and prompted massive intervention in currency markets by the Group of Seven industrial nations.

"It will take some time to rebuild, but it will not change the economic future of Japan," Buffett said on Monday on a visit to a South Korean factory run by a company owned by one of his funds. "If I owned Japanese stocks, I would certainly not be selling them.

"Frequently, something out of the blue like this, an extraordinary event, really creates a buying opportunity. I have seen that happen in the United States, I have seen that happen around the world. I don't think Japan will be an exception," said the 80-year-old investor, dubbed the "Sage of Omaha" for his successful long-term investment strategy.

Buffett heads Berkshire Hathaway Inc, which has substantial insurance and utility investments globally.

Japan's Nikkei share average rose 2.7 percent on Friday, buoyed by the G7 support, but still ended the week down around 10 percent, with some $350 billion wiped off share values -- the market's biggest weekly slide since the global financial crisis in 2008. Japanese markets were closed on Monday.

Buffett said Berkshire Hathaway, which at the year-end was sitting on $38 billion of cash equivalent and last week bought U.S. specialty chemicals maker Lubrizol for $9 billion, was looking for more large-scale acquisitions anywhere in the world.

In his annual letter to Berkshire Hathaway shareholders last month, Buffett had said he was looking for more acquisitions.

"The United States is most likely where we will do something," he said at a ground-breaking ceremony for a South Korean factory run by a unit of an Israeli firm owned by his investment vehicle.

Buffett will have yet more money to invest after Goldman Sachs buys back $5 billion of its preferred stock from Berkshire Hathaway, which the fund bought at the height of the global financial crisis.

EYE ON KOREA

Buffett, ranked the world's third-richest man by Forbes this year, said he was also looking to buy entire businesses and large-cap shares in South Korea -- where Berkshire is already a leading shareholder in steelmaker POSCO.

He said geopolitical risks associated with North Korea had not curbed his interest in South Korea, Asia's fourth-largest economy. Berkshire also owns a stake in Chinese car and battery maker BYD.

Buffett did not disclose any holdings in Japan on Monday, and Berkshire Hathaway's annual report did not show any major investments there. He had been due to visit Japan later this week, but canceled due to the earthquake.

Unlike many foreign fund managers, Buffett, who arrived in the southeastern city of Daegu on Sunday by private jet, won plaudits from ordinary South Koreans.

Sporting gray sweat pants and running shoes, Buffett was greeted by signs reading "Mr Buffett: Daegu Loves You."

Many in this country of nearly 50 million people have bad memories of the 1998 Asian financial crisis when a deal with the International Monetary Fund bailed out the country but at the cost of tens of thousands of jobs.

Some U.S. hedge funds have been branded "vultures" for buying South Korean assets on the cheap in the wake of that crisis.

"It's a once in a life-time opportunity. I'm honored to meet such a respected businessman," said Seo Hyun-joo, a housewife wearing Korean traditional dress.

Buffett later meets South Korean President Lee Myung-bak in Seoul and heads to India on Tuesday to launch his firm's insurance selling portal.