The easing of border restrictions and the coming school holidays has seen a surge in passport applications, with many worried they may not get their travel documents in time.

The Department of Internal Affairs' (DIA) Te Mata Uruwhenua says demand for passports has increased by 400 per cent since January, and there were 49,000 still to be processed - of which about 8600 are currently waiting for customers to respond to queries.

The department was also struggling with Covid absences that have hit almost a third of its staff at times.

Julia Wooton, the department's general manager services and access, said: "Teams are working additional hours, we have brought in extra staff from across the department, and have been recruiting and training new staff to meet the demand."

She said with couriers also experiencing high demand, it was taking up to six weeks to get passports to some applicants.

"Our team is dedicated to making sure Kiwis get their passports – we know how important it is," Wooton said.

An Auckland mother, who did not want to be named, said she made passport applications for her two children aged 12 and 14 in May but has still not received them.

They had made plans to visit family in Canada during the school holidays, starting July 9, but that can't happen without passports.

"DIA should have been prepared for increased applications with the school holidays coming and border restrictions eased," she said.

"This is not something unexpected, so it's no excuse."

The woman said due to the pandemic, this would be the first time in three years that they will be seeing their extended family again.

Wooton said standard passports are taking about one month to process, and "around half are taking less time, some more".

"We are working incredibly hard to bring these timeframes down, and to ensure our customers get timely communications from us about where their passport is in our queue," she said.

"Our best advice to customers is to allow for at least six weeks when planning their travel."

Wooton gave the assurance that urgent applications were still being processed within three working days.

"We are now processing greater numbers of applications each day than are received," she said.

"We are also improving the ways people can contact us and continue to scale up, while also dealing with ongoing Covid absences that have at times affected 30 per cent of our staff."

Another applicant said he found it impossible to apply for passports last weekend.

"The website does not permit the user to complete the submission, it goes to an error page once all the required steps are completed," said the applicant, who also did not want to be named.

"The phones are all disconnected, the physical offices are all closed and there are no responses to emails."

Wooton said services were temporarily halted during the long weekend for scheduled maintenance.

"Users were advised of the outage, which lasted between10pm on Saturday and 8am on Sunday, via a banner on the passports.govt.nz website," she said.

Wooton said the easiest way to renew or apply for a passport was online or by sending through a paper application form.