London Underground has admitted the signal system on the Jubilee Line extension - which is barely a year old - is failing due to 'growing demand'.
The line was extended as part of the government's plans to celebrate the Millennium and ease congestion for visitors to the Dome. But a spokeswoman for London Underground said increasing demand since the Dome closed has left the signalling system in need of repair.
She said: 'It's true the Jubilee Line will need to enhance its system to meet a growing demand. The best way would be to introduce an entirely new system which would cost around£100m.'
A spokeswoman for the DETR said the government provided grants for the Jubilee Line extension and it was always agreed there would be a replacement signalling system.
She added: 'The intention was always that it should be replaced so this is how we expected things to be going all along.'
Transport expert Bob Kiley, appointed commissioner of Transport for London after solving the Underground problems in New York, has so far spent all his time in the UK discussing the public/private partnership favoured by the government.
A spokeswoman for the Greater London Authority said: 'Mr Kiley deals with all London's transport, including the buses, roads and even walking, but he has no control over the way the Tube is run.'
Contractor Westinghouse said work carried out on the system so far was 'par for the course'.