Hundreds of thousands of people were affected by delays in processing passport applications and many had travel plans disrupted as a result, Whitehall’s spending watchdog has found.

HM Passport Office (HMPO) processed a “record number” of applications amid “unprecedented demand” as coronavirus pandemic travel restrictions were lifted but struggled to keep up with higher-than-average demand from customers, the National Audit Office (NAO) said.

In the first nine months of this year, 95% of customers received their passports within 10 weeks, but 360,000 people experienced longer waits.

The body urged the Home Office agency to learn lessons from the chaos and to “prepare for similar levels of demand” expected in 2023, when up to 10 million applications could be made.

Despite planning ahead, problems with recruitment and “limitations in its systems”, as well as unsuccessful efforts to deal with the level of demand all “contributed to longer than expected waits”, according to findings published on Friday.

During the pandemic, significantly fewer people applied for and renewed passports and officials planned for an “expected surge” in applications when travel restrictions were lifted.

The body prepared for 9.5 million applications in 2022 – 36% more than a normal year – based on the missing number of applications from the previous two years.

Between January to September, more than seven million people applied and the passport office processed 6.9 million applications, an increase of 21% compared with the same period in 2019.

HM Passport Office must now learn the lessons from this year and prepare for similar levels of demand that are expected in 2023

In May alone, more than 1.2 million applications were received, 38% more than the highest month in any of the previous five years. In the busiest week, 340,000 applications were submitted.

An estimated three million passport applications are still expected from people who did not renew or apply during the pandemic, which means the passport office could see a further 9.8 million applications in 2023, the report said.

Head of the NAO Gareth Davies said: “HM Passport Office processed a record number of applications amid unprecedented demand.

“But limitations in its systems, coupled with difficulties in keeping up with higher-than-average numbers of customers contributed to delays for hundreds of thousands of people, creating anxiety for those with travel plans and hampering people’s ability to prove their identity.

We recognise that a small percentage of British passport customers did not receive the service that they should rightfully expect earlier this year

“HMPO must now learn the lessons from this year and prepare for similar levels of demand that are expected in 2023.”

The department was already working to improve contact with customers and better deal with demand in future, the NAO added.

A Home Office spokesman said: “The impact of Covid-19 on passport services is not unique to the UK, with passport-issuing authorities across the world having reported challenges for their service.

“We recognise that a small percentage of British passport customers did not receive the service that they should rightfully expect earlier this year. However, we have worked hard to rectify this, and have processed a record number of applications for a British passport in 2022, with over 95% being completed within 10 weeks.”