PARIS (AP) -- European governments hurried today to calculate how many hundreds of billions of euros they will spend on an unprecedented 15-nation plan to save banks. That plan, along with action by top central banks to pump credits into the financial system, already appeared to be soothing markets.

Governments of Germany, France, Italy and Austria were today deciding the details and putting a price tag on the plan announced the night before at an emergency summit in Paris. France's Le Monde daily estimated the total European burden at a staggering euro1.3 trillion ($1.77 trillion).

In Europe's most unified response yet to the financial crisis, leaders of the 15 countries that use the euro currency agreed Sunday that individual governments would guarantee bank refinancing until the end of next year, rescue important failing banks through emergency cash injections and take other swift measures to encourage banks to lend to each other again.

Stocks markets rebounded today after the European decision and other weekend efforts to find solutions to the financial crisis, which has crushed major banks in both the U.S. and Europe and battered stock exchanges worldwide. Additionally, some short-term euro interest rates fell in a sign the measures may be having an effect on troubled credit markets.

Germany's benchmark index DAX jumped 6.44 percent to 4,836.88, France's CAC40 was up 6.47 percent at 3,382.01, while Britain's FTSE100 rose 4.82 percent to 4,121.73. Also helping markets was a joint move by the U.S. Federal Reserve, the European Central Bank and the Swiss National Bank to provide unlimited short-term credit in U.S. dollars to financial institutions. The Bank of Japan said it was considering similar measures.

Although European governments pledged to let any bank fail, there is no common European fund for this rescue plan -- the money is pledged by individual governments, so that no one country has to pay for the choices of the other ones.

Europe's biggest economy, Germany, put together a rescue package worth a total of as much as euro500 billion ($671 billion) to shore up the country's financial system, according to the Finance Ministry. Spain said it would guarantee up to euro100 billion ($135 billion) in bank bond issuance this year.

The head of the International Monetary Fund welcomed the European decision despite the high price it is expected to impose on state budgets.

"We must recapitalize the banks ... otherwise everyone will suffer," Dominique Strauss-Kahn said on France's Europe-1 radio today. "And that costs money."

The euro zone leaders who met yesterday have yet to sell their packages to voters at home, and analysts warned that governments and legislators could still balk. The overall cost will be heavy, especially on countries already in or on the brink of recession.

-- The Associated Press