Across the sector, unregistered teachers are a significant part of the teaching workforce. Any person working as a teacher must be vetted by the police every three years.
"We are in this crazy situation where we have ECE centres desperate for teachers and we have teachers wanting to start work immediately," Birch said.
"But because vetting results are taking so many weeks to come through, ECE centres are under impossible pressure because teachers can't be sent out to work."
Birch said ep.education, which works with large and small ECE centres across the country, is often waiting weeks for police checks with the oldest case dating back to April 14, 2021.
He said in some instances, by the time the results were returned, the teacher concerned had got sick of waiting and obtained work outside the sector.
"This problem is being talked about right across the ECE sector. Frustration and despair are growing as centres struggle to get the teachers needed to meet government staffing requirements."
Under the current system, every employer must do their own checks and Birch said some ECE teachers were being vetted four or five times, which was "an incredible waste of police resource".
"The obvious long-term solution is to complete police vetting once for each teacher, then give employers access to that information."
A similar system in UK education allowed portability of police vetting between one employer and another, with any updates or changes completed online.
Birch said the current situation cannot continue but a new system will take some time to put in place.
"It is critical that the police vetting team are immediately given the resources needed to clear this backlog and help ensure early childhood centres can be staffed in a way that is safe for children."
A police spokesperson said police were aware of a perceived "backlog" of vetting results for early childhood education teachers.
Police process about 600,000 vetting requests a year for about 13,000 approved agencies, with each request taking about 20 working days to process, the spokesperson said.
"We encourage all agencies to organise their vetting around this service level where possible, as it may not always be possible to prioritise applications."
However, the spokesperson said vetting processing timeframes can fluctuate throughout the year, based on the time of year, the complexity of the request, and whether the request meets the criteria for automation.
Between January and April, 206,000 vetting requests were received, which the spokesperson said was the "highest ever" received in that time period.
Despite that, the police vetting service was processing 64.2 per cent of vetting requests within 20 working days and 93.7 per cent within 28 working days as of Monday.
The spokesperson said the police service was pursuing opportunities for process and technology improvements to help reduce processing timeframes and improve its vetting service.
"We understand that some agencies on occasion need to use temporary staff at short notice and we acknowledge that our 20 working day service level can make using temporary staff difficult.
"To help agencies in this situation we are happy to work with them to create a pool of vetted temporary staff for them to safely utilise.
"We are also considering how an individual could request a vet on themselves and then enable them to share their vetting result with multiple organisations."
The police vetting service would maintain the validity of the vetting result to ensure the information remains up to date.
The purpose of the vetting service was to keep people safe, the spokesperson said.
"The risk is too high if we get it wrong."
Current vetting processing times were available on the police website, so organisations could see at all times of the likely timeframe for vetting requests to be completed.
Ministry of Education sector enablement and support deputy secretary Katrina Casey said they were aware of the delays in getting police vets and advised teachers in a newsletter this week to plan ahead, particularly with renewals.
She said vetting was an "essential" tool in keeping children safe and was a requirement before starting work, and needed to be renewed every three years.
Early learning services did not need to request a police vet for teachers, including relievers, who had a current practising certificate, she said, as the Teaching Council only approved a practising certificate once a police vet has been obtained and considered to be satisfactory.
