Central banks' efforts to ease strains in the money markets are failing to stop financial institutions from hoarding cash, stoking fears that the recent respite in equity markets may not signal the end of the credit crisis.

Banks' borrowing costs - a sign of their willingness to lend to each other - in the US, eurozone and the UK rose again even after the Federal Reserve's unprecedented activity in lending to retail and investment banks against weaker than usual collateral and similar action in Europe.