Animal and Plant Health Agency staff at Eden Bridge House will be taking strike action in their long running dispute on Monday, April 3.
Members of the Public and Commercial Services union will join fellow civil servants from the passport office and the British museum on the same day.
The dispute is over pay, pensions, job security and the redundancy scheme with the union calling on the government to enter negotiations to help avoid further strike action.
PCS General secretary Mark Serwotka said: “Our members are not backing down in this dispute.
"Ministers need to take notice that we’re escalating our action and they need to resolve the dispute by putting money on the table.
“We know our strikes have already caused serious disruption.
"The new strikes and another national day of action will pile the pressure on a government that refuses to listen.”
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