Passport workers could plan more strikes if they fail to reach a settlement with the government over pay and office closures.
The workers started a strike today for a three-day period delaying 60,000 passport applications and stopping holidaymakers who were planning to get a last minute passport from leaving the country.
Almost 3,000 workers striked at seven passport offices and 68 interview offices.
A Public and Commercial Services Union spokesman said: “We want to reach a negotiated settlement but can’t rule out further action.”