Rail workers are to be balloted on strike action over pay and pensions, the UK's biggest rail union has said.
The ballot will involve signallers, maintenance and station staff
If the 7,000 members of the Rail, Maritime and Transport (RMT) Union decide to strike, it could be largest action in the industry for a decade.
The union said the pay deal offered by Network Rail was worth 3% and the worst in the railway industry, while a new pension scheme was also inferior.
Network Rail said the threat of industrial action was "astonishing".
The two sides are also in dispute over travel facilities for workers.
The ballot will involve 7,000 signallers, maintenance and station staff.
The union's general secretary Bob Crow said: "The company has closed a decent pension scheme and imposed a glorified savings plan on our members, has refused to negotiate at all on travel facilities and has tabled the worst pay offer in the industry this year.
"This is a company which boasts of spending £14m a day, yet on the other hand says it cannot afford to maintain a decent pension scheme or end the divisive inequality in travel facilities."
He accused the company of continuing to pay six-figure salaries and large bonuses to directors while "squeezing the pay of the people actually go out and get the work done".
Mr Crow said: "Network Rail's short-sighted stance means a two-tier workforce with staff doing the same job getting different conditions and vastly different pensions."
He said those workers left in the scheme would have to pay more in contributions as fewer and fewer paid in.
But John Armitt, chief executive of Network Rail, insisted talks had not broken down.
He said: "We find the strike threat nothing short of astonishing as we are in the middle of constructive pay negotiations.
"There has not been a breakdown of talks. A variety of good deals are on the table for the unions to consider."
Network Rail said it had offered three different options, including a pay rise of 3.5% and the offer of a 35-hour week.
A second union, the Transport Salaried Staffs' Association (TSSA) is also considering balloting 4,000 members on strike action over allowances, pensions and travel facilities.
The RMT said a separate dispute with private firm Jarvis over job security and working conditions had been settled.
Jarvis staff had given the union a mandate for strike action amid concerns over possible job losses when workers were transferred to Network Rail.
Mr Crow said the union had accepted assurances there would be no compulsory redundancies arising from the transfers.