Tube maintenance workers have voted for an overtime ban as part of their industrial campaign against Metronet.

RMT union general secretary Bob Crow said the ban on overtime from Easter Monday would run for a week and could cripple the Underground network.

Mr Crow said more than 2,000 Metronet Tube maintenance staff would join the protest launched in a dispute over the forced transfer of staff to other companies.

He warned if the company failed to resolve the dispute by April 16, full strikes would be called as well.

RMT members at Metronet voted overwhelmingly both for strike action and for short of strikes after the company refused to withdraw plans to transfer staff to its parent companies, despite agreeing a year ago that it would not happen.

"Our members have demonstrated their anger at Metronet reneging on an agreement they made only a year or so ago," Mr Crow said.

"This dispute is about honouring agreements and defending our members' pay, conditions and organisation, but it is also about resisting dangerous fragmentation that our members already have too much bitter experience of.

"After consulting reps across the company the RMT executive has today agreed that a seven-day ban on all overtime working will begin at 18:00 on Easter Monday, April 9.

"That will have an immediate effect on traffic on two-thirds of the network, and will eventually completely paralyse the system.

"The door is open for talks to sort this dispute out based on the agreement we already have, but the executive has also made clear that strikes will be called if there is no sign of a resolution in a week's time."

Members of the Rail Maritime and Transport union (RMT) voted for industrial action by 750 to 60 - a 92 per cent majority.

Metronet has said any strike action would be unfair as discussions with the union were still continuing.

The dispute centres around a Metronet contract with its shareholder Bombardier signed in 2003 for the supply, maintenance and performance of 237 new trains for the Metropolitan, District, Circle and Hammersmith and Victoria lines, expected to start running in 2009.

Mark Cooper, Metronet senior vice president of asset performance, said part of the contract was to transfer train maintenance and performance responsibility to Bombardier and moving up to 700 staff to the company.

But since 2005, Mr Cooper said, the company has been working on a compromise, and only 250 staff, mainly managers and technical specialists will move with the other 850 staff staying with Metronet.

"Metronet and Bombardier have made ground-breaking compromises in order to put forward a viable alternative plan," Mr Cooper said.

"We have been working for more than a year to resolve this issue and will continue to work with the RMT to find an acceptable solution.

"Industrial action is not necessary and it is the traveling public who will suffer as a result.

"The plan on the table is a good plan and the one Metronet wants to see implemented.

"It sees the overwhelming majority of fleet staff remaining as Metronet employees."