According to the TSSA, 160 jobs, most of them from York, will move to the new centre in an initial phase. That will be followed by a second phase involving 60 jobs - all from York.

This will have an effect on the economy of York as well as a terrible effect on the members that we represent

David Chalkley, TSSA spokesman

Andrew Waller, the Lib Dem leader of City of York Council, said he would request an urgent meeting with Network Rail to clarify its plans.

"We need to get to the bottom of this because we must maintain our position as a railway city," he said.

Chief executive Iain Coucher said: "Network Rail spans Great Britain. We have 80 corporate offices across the country, but no national hub.

"Creating this heart for the business is an important step in delivering our long-term plans.

"That is why we have started planning ahead for a state-of-the-art centre based in Milton Keynes.

"Creating a national centre will make us better and innovative in the way we work, supporting our routes to deliver a better service for our customers and rail users."

The company said the new centre should be up and running by the end of 2011.

David Chalkley, of the TSSA, said: "Network Rail have consulted with the trade unions last week on the move of 200 jobs in the National Delivery Service from York to Milton Keynes.

"We are in the early days of consultation but these jobs are intended to move before the end of this year.

"This will have an effect on the economy of York as well as a terrible effect on the members that we represent who work in the York offices.

"At the moment our members are in a state of shock because either they have got to up sticks and relocate or they have got to find other work."