WASHINGTON\ — The Federal Reserve and other countries' central banks announced new steps today that makes billions of dollars available to squeezed banks here and abroad to battle a worsening credit crisis that threatens to unhinge the U.S. economy.

The Fed said the action is intended to "expand significantly" the availability of cash available to financial institutions in an effort to provide relief to the worst credit crisis since the Great Depression. In taking the action, the Fed cited "continued strains" in the demand for short-term funding.

Central banks will continue to work closely and are prepared to take "appropriate steps as needed" to stem the fallout, the Fed said.

Under one new step of relief, the Fed will boost the amount of 84-day cash loans available to U.S. banks. The Fed is increasing the amount to $75 billion, up from the current $25 billion starting on Oct. 6. Banks bid on a slice of the loans at an auction.

All told, the move will triple the supply of 84-day loans to $225 billion from $75 billion, the Fed said.

The Fed also said it will supply $330 billion to other central banks, expanding ongoing currency "swap" arrangements with them where dollars are traded for their currencies.

The move comes as the U.S. financial meltdown's tendrils have ensnared banks in Britain, the Benelux and Germany.