Washington Mutual, the troubled US regional lender, on Friday revealed it had taken steps to bolster its available liquidity by $10bn in fresh capital since the end of June in an effort to quell continued speculation over its financial health.

WaMu told the Financial Times the extra capital would bring the total amount of cash and liquid securities on its balance sheet to more than $50bn. The funds were borrowed from the Federal Reserve’s discount window, the Federal Home Loan Banking system – a network of local lenders – and open market operations.