The biggest disruption on the railways for a decade was looming last night after thousands of signal workers and maintenance staff backed strikes in a dispute over pay and pensions.

Members of the Rail Maritime and Transport (RMT) union employed by Network Rail voted by 58 per cent in favour of walkouts, threatening travel chaos across the country from next month.

The union held back from naming strike dates and assured travellers there would be no action over the Bank Holiday weekend or during events marking the 60th anniversary of D-Day on June 6.

Network Rail warned that a strike would be deeply damaging and started drawing up contingency plans, including special timetables and retraining former signalling workers. The head of the Confederation of British Industry accused the union of being irresponsible and warned that Britain's reputation as a place to do business would be seriously damaged.

The Government said the last thing passengers needed was a strike which would cause massive inconvenience.

The RMT has warned it might co-ordinate strike action on the mainline railway with London Underground, where union members are involved in a separate pay dispute.

General secretary Bob Crow announced the ballot result at the union's London head office and launched an attack on a decision by Network Rail to change its pension scheme for new entrants.

Union members voted by 2,947 in favour of a strike, with 2,246 against, in a high turnout of 68 per cent.

Mr Crow said the union's executive would meet next week to decide what form of industrial action would be held.

He wrote last night to Network Rail's chief executive John Armitt asking if the company was prepared to hold serious negotiations.

Announcing the ballot result, he said: "Despite a venomous and misleading propaganda campaign by Network Rail, our members have voted for action to defend their pension rights, to end two-tier working conditions and for justice on pay.

"Network Rail's directors are happy enough to hand themselves telephone number bonuses but when it comes to the workforce it is a completely different story.

"Without a word of negotiation, they have closed a decent pension scheme and imposed a cheaper, inferior scheme no better than a glorified savings plan.

"Our members have made it clear that their pensions are not an optional luxury that can be cut to help boost the bosses' bonus fund."

Mr Crow said the 58 per cent majority was a comfortable vote in favour of strikes and made it clear that disruption would go ahead unless the deadlock was broken soon.

The Strategic Rail Authority said that every day a strike was held money would be lost to settle the dispute.

A spokesman said: "This is a mad strike. Every day a strike lasts the amount of available money for pay rises goes down. Only RMT members can stop this."