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 per cent on Friday, buoyed by the G7 support, but still ended the week down around 10 per cent, 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

David Fuller's view When has a disaster in a developed economy not proved to be a buying opportunity, once the dust settled? Fullermoney warmed to Japan's stock market in 4Q 2010 but are the country's medium to longer-term economic prospects better or worse, following the earthquake / tsunami and crisis at the Fukushima?

It may seem like a paradox, but I would say that prospects are probably better, provided the deteriorating situation at Fukushima is close to its nadir. Yes, Japan's economy will be hit hard for a quarter or two but its people, government and central bank have been galvanised into action with a common purpose to rebuild Japan. They will almost certainly make it better than it was before this month's crisis. Moreover, Japan's allies have already shown that they will help it to break the yen's upward spiral, most likely halting deflation in the process. (See also Eoin's comments below.)