Network rail is poised to announce 2,500 job losses in a move aimed at cutting costs over the next few years.
The Rail, Maritime and Transport Union said the job cuts will be phased until 2006 and will be spread across the company, which employs more than 14,000 workers.
Network Rail would not confirm the job cuts last night, but it admitted that details of an efficiency programme will be announced in the early part of next week.
The company is aiming to reduce costs by 20 per cent, or £1bn a year, following a huge increase in overheads following the demise of Railtrack.
Network Rail has asked the rail regulator for an addition £12bn to run the railway over the next five years, but is unlikely to get anywhere near that amount.
A spokesman said: "Driving down costs and improving performance are Network Rail's main focus.
"Head count is one area that we are looking at as part of our efficiency improvement programme and we hope to release more details early next week."
The revelation plunged the not-for-profit company into a fresh controversy after a row earlier this week about executive pay.
Unions, passenger groups and politicians reacted with anger after it was revealed that directors received bonus payments totalling £1.8m last year, even though trains were still running late.
No performance related bonuses were paid to executives at Network Rail, which succeeded Railtrack after it went into administration last year. However, a number of "retention" payments were made.
Bob Crow, the general secretary of the RMT, said job cuts on such a big scale would be "obscene". He added: "It is huge bonuses for the directors and P45s for the rest.
"We will resist any compulsory redundancies, with industrial action if necessary."
Network Rail employs signalling staff, engineers, administration workers and other employees.Reuse content