LONDON -- International stock markets hemorrhaged hundreds of billions of dollars yesterday, as countries scrambled to save their own banks and bolster whatever investor confidence remained.

Markets plunged in nations from Brazil to Saudi Arabia, as some indexes saw their steepest drops in 20 years. Precipitous falls halted trading on several exchanges.

The Paris bourse fell 9 percent, Germany's main index tumbled by 7 percent and the London FTSE 100 dropped by 8 percent, losing the most points in a single day's trading in its history and wiping out more than $150 billion in value. Russian stocks plummeted even more, by nearly 20 percent.

Across Europe, governments have sought to contain the damage by guaranteeing deposits and cobbling together bailout packages for struggling financial institutions, including some of the biggest names in European banking. But those efforts failed to stem the flight from the markets.

"No bones about it, this is a whole lot worse and scary than anything I've ever seen," said Peter Bickley, chief economist for the British arm of Germany's Deutsche Bank.

Even as countries blame the United States as the cause of the financial crisis, they are finding their own banks affected by and implicated in it.

But a coordinated defense, especially among the 27 members of the European Union, has proved elusive in spite of public pledges by leaders to unite against the most sweeping global financial threat in a generation.

Ireland's decision last week to back all deposits in its banks angered fellow EU states for its unilateralism, but triggered a rush by other governments to do the same. Greece quickly matched the plan, Germany made a similar promise Sunday, and Iceland -- which is not part of the EU, but has been hit hard by the spiraling crisis -- followed suit yesterday, declaring that it stood ready to take control of the nation's commercial banks.

Brazil, Latin America's largest economy, was forced to stop trading twice in its financial capital, Sao Paulo, when the Bovespa index declined 10 percent and then fell to 15 percent, tripping so-called circuit breakers. It eventually rallied to close down about 5 percent. The Brazilian real slid to its lowest level in more than a year against the dollar, mirroring similar devaluations for other world currencies including the euro, which fell below $1.35; in July, it was trading around $1.60.

In Mexico, the IPC index slid 5.4 percent, as traders blamed volatility for a sharp drop in the peso, which fell to 11.8 to the U.S. dollar -- its lowest level since 1993.

Russia's RTS index yesterday posted its largest one-day loss since trading began in 1995; the drop was partly the result of slumping oil prices. Deputy Economic Development Minister Andrei Klepach warned that the government's recent projection of $30 billion in capital inflow this year could dwindle to nothing.

Stocks also dived in Saudi Arabia and other Persian Gulf states that have witnessed big building booms in recent years. Real-estate shares in Dubai, at special risk because its growth has been fueled more by residential and commercial development than by its oil supplies, closed down 7 percent.

In Asia, Japan's Nikkei 225 index lost 4.25 percent yesterday to close at its lowest since February 2004. China's Shanghai Composite Index fell 5.2 percent.

After its first attempt at a bailout collapsed, the German government brokered a $68 billion deal with its finance industry to save Hypo Real Estate, one of the country's largest lenders.

In Brussels, Belgium, the hastily put-together acquisition of Belgium's Fortis bank by the French giant BNP Paribas over the weekend failed to calm jitters over French-Belgian bank Dexia, whose shares plunged about 20 percent. Belgian government officials met with shareholders yesterday to discuss the bank's health and whether it might require a rescue.

And in Italy, the board of Unicredit Bank, whose top manager pronounced it as solid only a week ago, negotiated an emergency package over the weekend to raise $4 billion in new capital and proposed to pay investor dividends with new shares rather than cash.

There was still no prospect of a Europe-wide bailout package akin to the $700 billion U.S. plan approved last week. Although France has floated such a proposal, opposition from Germany, Europe's biggest economy, has kept the idea from gaining traction.

The 27-member European Union has shown little appetite or ability to act as a collective, despite assurances yesterday by French President Nicolas Sarkozy, who currently holds the EU presidency, that "European leaders recognize the necessity of close coordination and cooperation."