British passport holders face a summer of disruption as a planned five-week strike by passport staff is set to begin on 1 June.
The Public and Commercial Services union has called for members to take industrial action in a dispute over pay and staffing levels.
The strike could affect the processing of passport applications, renewals and replacements, as well as other services including visas and identity cards.
The union said it had been left with no choice but to take action after the Home Office failed to offer a reasonable pay rise.
The union is pushing for a two percent pay rise for passport workers, which it says would restore their previous real-terms pay cut.
The Home Office has said it is disappointed that the union has chosen to take industrial action, but that it remains committed to finding a resolution.
The strike is set to run until 1 July, and will coincide with the peak summer holiday period, when many British travellers are applying for or renewing their passports.
The Home Office has advised those applying for or renewing passports to apply as early as possible and allow longer for the processing of applications. It has also warned that processing times could be longer due to the strike.