LONDON -- Five central banks acted Thursday to shore up confidence in Europe's financial system by giving its banks far greater access to U.S. dollars.

The move buys time for banks that hold large amounts of debt issued by Greece and other financially troubled European countries. Some of these banks have had trouble paying for daily operations because other banks have refused to lend to them any more.

Under Thursday's action, the banks can borrow unlimited dollars for three months, up from the current one-week limit.

The European Central Bank said it will coordinate with the U.S. Federal Reserve, the Bank of England, the Bank of Japan and the Swiss National Bank to offer the loans through the end of this year. Their move to supply more dollars is similar to steps taken during the 2008 financial crisis and again in May 2010.

Concern about their access to dollars has been a key reason why European banking stocks have been beaten down. Investors have been particularly worried about big French banks Societe Generale and BNP Paribas. Thursday's news sent Societe Generale's stock soaring 8 percent and BNP Paribas' 13 percent.

Analysts cautioned that the expanded credit line for dollars isn't a long-term solution to Europe's debt crisis. Greece still appears likely to default on its debts. If it does, some banks could topple. Panic might spread among global investors.

The move will likely ward off a panic for the next few months, said Mark McCormick, currency strategist at Brown Brothers Harriman

"But it's not going to solve the problem, which is too much debt," McCormick said.

Daniel Alpert, managing partner at the New York investment bank Westwood Capital, said the move allows European policymakers to work through the end of the year to prevent a Greek default from upending the global financial system.

"They're gearing up to allow an orderly default" by Greece and to prop up banks that suffer big losses on bonds issued by Greece and other financially ailing countries, Alpert said.

It provides "some time to put institutional firewalls in place so that the whole place doesn't melt down," he said.