Alistair Darling has offered to bring forward the appointment of a US-led team nominated by Ken Livingstone to manage London Underground.

Despairing of the current management, the transport secretary has suggested that Tim O'Toole, an American rail freight boss lined up by the mayor, should become managing director immediately.

The government is said to be disappointed with LU's handling of the aftermath of the Chancery Lane crash, which led to an 11-week closure of the Central Line.