Share prices plunged Thursday on the Tokyo Stock Exchange after the Bank of Japan's quarterly "tankan" survey showed a dramatic fall in business confidence.

The benchmark 225-issue Nikkei average plummeted 538.76 points, or 3.3 percent, to 15,702.90, its lowest since Jan. 14. The gloom in the financial market deepened as the tankan offered fresh evidence of an ailing economy.

The survey, taken in March, reveals that business confidence in major manufacturing industries has plunged to its lowest point since August 1994. The BOJ report triggered selloffs almost across the board. Notable losers included banking and construction issues.

The BOJ survey revived credit risk fears for banks, said Hideaki Akimoto, chief strategist at Daiwa Institute of Research Ltd. A major factor behind demoralized investor sentiment, according to Akimoto, is what he described as the overwhelming lack of government support.

Unless the government commits itself to sizable income and corporate tax cuts, the Nikkei average could soon plunge as low as 15,000, Akimoto said. The government has announced in recent months plans for a series of economic stimulus packages, but their contents remain largely unknown and the market remains unconvinced that they will be effective, Akimoto said.