Large US investment banks will be able to access emergency cash from the Federal Reserve into next year if market turmoil persists, Ben Bernanke said on Tuesday in a sign of the growing concern among policymakers that financial strains could continue for some time.

The signal from Mr Bernanke is likely to soothe Wall Street, in that it confirms Fed support for investment banks through the credit crisis. US stocks rose on Tuesday, the dollar rallied against the euro and oil prices staged their biggest retreat in months.