Blunder causes huge delays

A Tube engineer who is said to have used a hammer instead of a spanner and damaged signalling equipment was today blamed for causing long delays for tens of thousands of commuters.

The incident happened at about 7am when a track gang employed by Tube Lines, the private-sector consortium in charge of maintaining the Jubilee line, were replacing an iron "chair" - one of the brackets which hold the track to the sleeper - just outside Baker Street station.

But after the work was completed, it was found that the chair was causing a short-circuit with the signals. The fault caused multiple signal failures and knocked out a large section of the Jubilee line for the morning peak.

Services did not resume until 9.30am and then only with severe delays. A Tube source said: "There are bolts which secure the chair. These are screw bolts but a hammer was used and damage caused to the parts."

A London Underground spokesman confirmed that delays had been caused "because of very poor overnight engineering work by Tube Lines".

He said a "full explanation" was now being demanded.

But a spokeswoman for Tube Lines described the claims of an engineering blunder as a "Chinese whisper".

She confirmed, however, that a short-circuit had been found while replacing the chair. A Tube Lines emergency response team was sent to deal with it and used different fittings as an emergency measure to get trains running again.

The spokeswoman said: "Because they were different fittings a hammer was used. This was the correct tool." Proper repairs would be carried out tonight, she added.

Meanwhile further, unrelated, signal failures and other faults caused chaos across a large part of the Tube network.

The Metropolitan, Northern, Bakerloo, Circle and Hammersmith & City lines all suffered disruption and cancellations.

Mayor Ken Livingstone has accused the privatesector companies of constantly failing to do their job properly - despite each making tens of millions of pounds profit.