The week-long action by hundreds of workers will now continue while new moves are made to resolve the dispute.

Leaders of the Amalgamated Engineering and Electrical Union met officials from contractors Drake & Scull on Monday night to put forward fresh proposals aimed at securing a return to work.

But Project Director Chris Raven dashed hopes of a deal on Tuesday, saying the proposals did not provide a way forward.

"The shop stewards have not moved on any of the key issues," he said.

More talks

They were still insisting that 12 workers should not be transferred from the London Bridge site to Green Park, the issue which caused the strike last week.

"We will continue to hold discussions with the union, which has tried hard to get the men to return to work, but unfortunately it has not succeeded," he said.

The strike was a "concern", but Mr Raven said he believed the work could be recovered quickly if the men return to work and to full productivity quickly.

The electricians have raised safety fears and have picketed stations on the line in recent days, displaying banners reading: "Fast track to the grave."

The strike is causing further delays to the troubled 10-mile extension, which has been hit by a series of technical problems and disputes.

Last week it was alleged that cables had been cut in an act of industrial vandalism.

The tube line, which is being extended to carry more than half a million people from central London to the Millennium Dome, is already several months behind schedule.

It is now due to be completed in autumn 1999.