Urgent appointments to renew or replace a passport are unavailable as demand surges on the first day of a five-week strike.
The online premium service – which allows people to get a new passport in two days – is currently unavailable due to “high demand”.
There are also no appointments available for the one week fast track service.
People can still apply for a new passport via the standard service, but the Government advises that this takes up to 10 weeks from when the Passport Office receives the old document.
But the head of the PCS union, which represents striking Passport Office workers, has said that the maximum 10-week wait will increase as a result of the walk-out.
“There are 1,900 staff directly involved in decision-making on new passports, renewal applications and sitting on reception areas,” Mark Serwotka told Sky News on Monday. “Of those, 1,600 will be on strike, so it is inevitable that delays will increase, queues will increase.”
Last year, families were forced to miss out on holidays after severe delays in the Passport Office caused havoc for people awaiting renewals.
The Passport Office’s urgent renewal services were only intermittently available with very few appointments, if any, available each day.
Many people were forced to cancel trips abroad after their passports were held up longer than the 10 weeks they had been advised to allow.
A backlog of more than 550,000 passports was still waiting to be processed at the end of June 2022. In December, a report by the National Audit Office (NAO) found that around 360,000 people had to wait longer than 10 weeks for their passports to be renewed in the first nine months of the year.
The Home Office said the Passport Office has already processed more than 2.7 million applications this year, with over 99.7 per cent of standard applications being processed within 10 weeks and the majority of those delivered to customers well under this timescale.
More than 4,000 people are employed by the Passport Office across the UK, meaning that according to the union figures around one in four workers will walk out as part of a long-running dispute over pay, jobs pensions and conditions.
The Home Office says the strike does not affect its guidance which is still to allow up to 10 weeks to get a passport, with preparations under way to meet demand.
The offices affected are in Glasgow, Durham, Liverpool, Southport, Peterborough, London, Belfast and Newport.
PCS general secretary Mr Serwotka has written to the Government calling for urgent talks to resolve the dispute.
He has accused ministers of treating Government employees differently from other public sector workers after negotiations were held with health and teaching unions.
The civil service strikes are due to escalate later this month, with a mass walkout of more than 130,000 unionised Government employees planned for 28 April.