LONDON — Jitters about the American economy sent global stock indexes lower again today before the Federal Reserve’s surprise cut in interest rates. The move came too late for Asian markets, which had closed for the day, but helped Britain and France rebound higher.

Asian stocks began global trading sharply lower on fears of a recession in the America with Japan’s Nikkei 225 index off 5.7% — its biggest percentage drop in nearly 10 years — and Hong Kong’s Hang Seng index down 8.7%.

European stocks had fallen sharply at the opening, then rose in volatile trading ahead of the Fed’s decision to cut its key rate to 3.5% from 4.25%, and rose even more afterward. Birtain’s FTSE 100 finished up 2.9% at 5,740.10, while France’s CAC 40 gained 2.1% to 4,842.54. In Germany, the DAX ended barely down, off 0.3% at 6,769.47, as utilities RWE and E.On fell but financials such as Deutsche Bank rose.

The surprise Fed move was aimed at fears that trouble in financial markets from the American subprime crisis was spreading to the broader economy. Interest rate cuts tend to boost stocks. The Canadian central bank quickly followed, lowering its key rate by a quarter of a percent to 4%.

Just hours before the Fed decision, Japan’s central bank voted unanimously to leave its benchmark interest rate unchanged at 0.5%. The European Central Bank — highly sensitive to any suggestion that it is not fully independent — also held steady at 4%.

Some analysts now say the ECB — which has been worried about inflation — may have to follow the Fed and start cutting later this year.

European officials, however, insisted today that their economies would be able to weather the turbulence from America. The European Union’s economic and monetary affairs commissioner, Joaquin Almunia, said that big American trade and budget deficits were to blame. “The main reason why the equity markets have this extreme volatile situation these days is the risk of a recession in the U.S., it’s not about a global recession,” Mr. Almunia said.

A spokesman for Prime Minister Brown of Britain, Michael Ellam, said that “the fundamentals of the British economy have remained sound” and the government would do everything in its power “to maintain economic stability.”

But Mr. Ellam would not comment on whether British interest rates should be cut in response. Many observers believe the Bank of England, which is independent of the British government, will cut rates at its next meeting February 7.

Before the Fed’s move, the Nikkei nose-dived to 12,573.05, a day after falling 3.9%, and the Hang Seng added to its 5.5% drop yesterday. Australia’s benchmark index sank 7.1%, its steepest one-day slide in nearly 20 years. In China, the Shanghai Composite index lost 7.2% to 4,559.75, its lowest close since August.

Finance Minister P. Chidambaram of India urged investors to remain calm after trading in Mumbai was halted for an hour when the stock market there fell 10% within minutes of opening. The Sensex climbed back to close down 5% after plunging 7.4% yesterday.

“There is no reason at all to allow the worries of the Western world to overwhelm us,” Mr. Chidambaram said.

Investors had dumped shares in frenetic trading on worries that the American economy, battered by a credit crisis and housing slump, will shrink in coming months, weakening demand for exports. There is also skepticism that American authorities will be able to prevent a recession.

The Federal Reserve has indicated it will lower interest rates further, and President Bush has proposed an economic stimulus package that includes about $150 billion in tax cuts — but investors around the world have been doubtful that the measures will lift the economy quickly.

Noritsugu Hirakawa, who monitors stock trading at Okasan Securities Co. in Tokyo, said investors were spooked by the drastic declines on Chinese and Indian markets — two emerging economies that are viewed as sustaining global growth even as the American economy sputters.