Security guards and laundry workers based at the Sellafield site will go on strike for a total of 20 days over pay.

Union members of Unite, which also includes catering and vending staff, work for outsourcing firm Mitie at the West Cumbrian nuclear complex.

The union says the workers are paid £8.45 an hour and are demanding staff are paid more, but the company "has refused to allow Unite a seat at the negotiating table".

Members took part in a ballot and its 180 members voted by 98 per cent in favour of strike action on a 70 per cent turnout.

Unite has announced two 10-day strikes.

The first will start at 12.01am on Friday April 19, ending at 6am on Monday April 29, followed by a further strike beginning at 12.01am on Saturday May 4, ending at 6am on Monday May 13.

Members will also stop overtime shifts from 12.01am on Friday, April 19.

Unite regional officer Ryan Armstrong said: “Mitie is a multi-million pound company that is refusing to pay workers even the living wage, on a high security site.

“Our members are no longer going to accept poverty wages and if Mitie wants to prevent huge disruption at the complex, then it needs to make a fair pay offer.”

A spokesman for Mitie said: ""GMB is the only recognised union on our soft services contract at Sellafield. This continues to be a constructive relationship.

"Following recent successful pay negotiations with the GMB, we have increased hourly rates for employees on both contracts.

"These offers were accepted following a ballot of GMB union members.

“We are arranging cover to ensure the normal continuation of services across the sites and minimalise any potential disruption."