Network Rail says the public are against a strike

About 7,000 maintenance and signal workers belonging to the RMT union backed action against Network Rail.

The union did not name strike dates immediately. There are fears it could coincide with a separate strike on the London Underground.

Network Rail said a strike could be "deeply damaging" and would jeopardise recent performance improvements which had seen punctuality at a four-year high.

The strikes are set to be the worst in nearly a decade, when a dispute over pay in the run-up to privatisation brought the railways to a virtual standstill.

Turnout for the ballot was 68% with 2,947 union members voting in favour of a strike and 2,246 against.

Announcing the ballot result at the union's London head office, RMT general secretary Bob Crow said the union would be consulting local and regional representatives over the next four or five days.

He said they would discuss possible dates for industrial action and what form it would take.

Final salary pension

"If the company want to reopen negotiations by then we are prepared to talk," he added.

He promised there would be no disruption during the May bank holiday weekend or to coincide with events to mark the 60th anniversary of D-Day.

Mr Crow said the workers' action was "to defend their pension rights, to end two-tier working conditions and for justice on pay".

And he launched a fresh attack on a decision to stop new staff entering the final salary pension scheme.

He said: "People retiring in 20 to 30 years time are going to have no state pension, company pensions won't be worth a light and they will be going to the taxpayer to keep their heads above water."

'Huge bonuses'

Network Rail warned every 24-hour strike would cause losses of between �12m and �15m.

"Every single day the RMT is on strike, the pay available to settle the dispute goes down.

"The 3.5% being offered by Network Rail is worth �21m, so that would be wiped out within two days of a strike," a source said.

It also pointed out that, with less than half of the company's operations and maintenance staff in the RMT, and 38 of these voting for a strike, less than one in five supported the action.

A statement added: "The company will endeavour to run as many train services as possible during any strike, although plans cannot be finalised or released until closer to the day of any potential strike action in order to gauge the numbers of key staff available."

Chief executive John Armitt said the union had failed to fully inform its members of the facts and the offers made and called it "a pointless and unnecessary dispute".

Transport Secretary Alistair Darling said the action would cause "massive inconvenience and needless disruption to the travelling public".

"At a time when improvements are starting to come through on the railway and passenger confidence is improving, the last thing passengers need is a strike."