The cost of insuring top quality US companies against default hit a record high on Tuesday even as Hank Paulson and Ben Bernanke told Congress that their radical policy actions to ease the credit crisis were starting to bear fruit.

“We have turned the corner in terms of stabilising the system and preventing collapse,” said Mr Paulson, Treasury secretary. He called for patience, saying: “There is a lot of work that still needs to be done in terms of recovery of the financial system.”