Asian stock markets tumbled Wednesday, with Japan's Nikkei index sinking nearly 10 per cent, as recent steps by the world's major economies to fortify credit markets failed to stem fears that the spreading financial crisis could spawn a global recession.

After a miserable day on Wall Street when the Dow Jones industrials lost more than 500 points, investors in Asia responded by dumping stocks in a broad regional sell-off.

Japanese shares were hammered hard, with the benchmark Nikkei 225 stock average spiraling down nearly 10 per cent to 9,159 in afternoon trading to its lowest intraday level in five years.

Shares of Toyota Motor Corp. sank 12 per cent on reports that its operating profit would fall 20 per cent in the fiscal year through March.

"Selling seems almost unstoppable because of uncertainty over the crisis," said Kazuki Miyazawa, market analyst at Daiwa Securities SMBC Co. Ltd. in Tokyo. "Investors simply don't find incentives to buy stocks."

The carnage was also brutal in Hong Kong, where the blue chip Hang Seng index plunged 5.6 per cent to 15,871.

To ease the credit crunch, Hong Kong's de facto central bank said it will cut the benchmark interest rate by 1 percentage point to 2.5 per cent. The move represents a break from Hong Kong's traditional pattern of following the U.S. Federal Funds target rate, which is now at 2 per cent. The authority said it has changed its formula to calculate its base rate from 150 basis points above the prevailing U.S. fed funds rate to 50 basis points.

Australia's benchmark S&P/ASX200 shed 5 per cent, wiping out a 1.7 per cent gain on Tuesday after the country's central bank cut its key interest rate by a larger-than-expected 1 percentage point.

Asian markets were deep in the red: South Korea's benchmark index was down 6.1 per cent, Thailand's market was down 6 per cent, and Indonesia's stock market halted trading when its key index plunged 10 per cent.

Investors in Indonesia seemed to be dismissing comments by the central bank governor Tuesday that Indonesia will avoid the worst of the global credit crisis. On Tuesday, the central bank raised interest rates a quarter percentage point, citing a two-year high in inflation.

"People are very, very nervous that Europe will get belted tonight as they didn't see a lot of the late losses in the U.S. session, and people just think it's going to get worse," said Ric Klusman, an institutional dealer with Aequs Securities in Sydney.

In New York Tuesday, the Dow lost more than 5 per cent despite efforts by the Federal Reserve to reinvigorate the dormant credit markets by invoking emergency powers to lend money to companies outside the financial sector and buy up mounds of commercial paper, the short-term debt that firms use to pay for everyday expenses like salaries and supplies.

Federal Reserve Chairman Ben Bernanke warned in a speech Tuesday that the financial crisis could prolong the difficulty the economy is facing. While his remarks were widely regarded as a sign that an interest rate cut could be in the offing, Wall Street appeared little comforted and focused on his downbeat assessment.

In currencies, the dollar weakened slightly to 101.25 yen in Asia early Wednesday afternoon from 101.38 yen late Tuesday. The euro stood at $1.3585 compared with $1.3550.