The US Federal Reserve said yesterday it was extending the life of three emergency lending programmes aimed at thawing the credit markets in the light of the continuing turmoil in the financial system.

The move comes a day after Ben Bernanke, the Fed chairman, said the economy remained under "considerable stress" and made it clear that policymakers would use unconventional central banking tools in addition to interest rate cuts to support it, such as buying long-term government bonds.