As a wildcat strike by electricians on the project entered its third day, it was revealed that essential cables had been cut at a cost of more than pounds 100,000.
Workers have also been accused of attempting to intimidate managers. In one incident, excrement was daubed on a supervisor's office door.
Management and employees' representatives met yesterday in an attempt to resolve the problems, which union sources say amount to "industrial anarchy".
More than 400 electricians walked out on unofficial strike on Monday in protest at the transfer of 11 workers from the line's London Bridge site to Green Park. The men were said to be furious because a safety representative, who pointed out deficiencies in fire alarms, was one of those moved.
A source at the Amalgamated Engineering and Electrical Union, which represents a large majority of workers on the project, said he expected the talks to be "heated". "If our people are responsible for sabotage, there will be hell to pay. We will take a very dim view indeed," he said. But he added that if London Underground was intent "on pointing the figure" at AEEU members it would only serve to lengthen the unofficial strike.
Management acknowledged that the sabotage, which involved the sprinkler systems on escalators at London Bridge, was only the latest in a series of incidents. The damage will add four weeks to the project, which is already 18 weeks behind schedule.
Peter Mandelson, the Secretary of State for Trade and Industry, who is overseeing construction of the Millennium Dome at Greenwich, is anxious that the pounds 3bn line be completed in time to link central London with Britain's main millennium attraction. The line is due to be completed next autumn, but the disruption throws doubt on whether it can be finished on time.
Paul Gover, manager of the project at London Bridge, said there had been acts of vandalism over several months. The damage to the escalators was a "malicious and spiteful act.
"We cannot understand why anyone should commit these acts," he added.Reuse content