One of a market town's biggest employers could be forced to leave with the loss of 350 jobs.

Angry workers at the Rural Payments Agency (RPA) in Northallerton, North Yorkshire, are launching a campaign to stay and have called on local MPs William Hague and Anne McIntosh for support.

The jobs bombshell came during a regular roadshow with managers of the RPA, part of the Department for Environment, Food and Rural Affairs.

It was revealed that the private lease on its building, Alverton Court, was being renegotiated as part of Government cost-cutting moves.

One option is to move to an outside Government-owned site, possibly in York or Newcastle.

Natural England, another government group, employing around 50 people in the same building is moving to York.

It is understood negotiations to extend the contract on more favourable terms, because RPA will be using only around two thirds of the site, have so far been unsuccessful and have been further complicated because the landlord is based outside the UK.

Managers have said their preferred option is to stay in Northallerton. The lease runs out in March 2014.

Dave Berry, assistant secretary of civil service union PCSefra group, said workers were stunned and shocked, not only at the news but at the way they found out.

“Staff are really concerned and this would be a terrible blow for the town. If they relocated, how do we deal with 350 people who live and work here? There would be some potential to transfer to other offices, but there are a lot of people who are tied to the farming and rural community, many have young children.

“Workers were unhappy that this only came out during general discussions at a roadshow, this is their future. We are launching a campaign to bring pressure to bear to try and make sure the right decision is made for the people of Northallerton.”

A spokesman for the RPA insisted no decision had been made about the future of the office.

“There is a lease break at Alverton Court in 2014 and as with all agencies and departments across Government, we have to explore every opportunity to ensure that the Agency and the taxpayer are getting value for money.

“We are working hard to ensure that we get to a decision point about the office so that we can provide clarity and certainty to our people as soon as possible.”