The trade union representing thousands of workers at Britainís Home Office has advised that staff will go on strike the day before the London Olympics open.
The action will involve staff across the Home Office, including the UK Border Agency, the Identity and Passport Service and Criminal Records Bureau.
The Public and Commercial Services said its members will strike for 24 hours next Thursday - when many thousands of visitors are due to arrive in the UK.
Home Secretary Theresa May has described the action as shameful saying it threatens disruption to people travelling to London for the Games.
Immigration minister Damian Green said contingency plans are to be put in place.