Schools and childcare centres are short of teachers because of a new law requiring police vetting for workers responsible for children.
The changes have meant some children with learning difficulties have been unable to attend school fulltime.
More than 53,000 people are in a seven-week queue to have their criminal records checked and the police vetting service is being boosted to deal with the workload.
Schools, childcare centres and other agencies working with children say they have new staff ready to work who can't start without police clearance and children are being disrupted with different relief workers.
The bottleneck has been caused mainly by the Vulnerable Children Act, which from Wednesday requires all new employees in state-funded jobs who may be alone with, or have primary responsibility for, anyone under age 17 to be vetted.
The same requirement is being phased in over the next four years to cover 280,000 new and existing state-funded workers who work with children in any capacity.
Police confirmed that 53,565 applicants were in the queue on Friday, compared with 15,000 a year ago, and that the average waiting time had blown out from 20 working days to 37 working days.
Principals Federation president Denise Torrey said she knew of one child who could not attend school fulltime until the school got a police clearance for a teacher aide.
Sue Bennett of Campus Creche at Waikato University said she had about five people who had applied to be relievers who could not be employed until their checks came through. That meant the creche had to recruit from an agency.
"It's been hard for the children indirectly because [by] going to an agency, you don't always get the same relievers, so there's not the continuity.
"The babies don't like having a whole lot of new people to look at.
"The whole crux of a successful early childhood centre is the relationships that are built, so if we're having to ring up the agency and they can't always send the same person, then that becomes really difficult."
Early Childhood Council chief executive Peter Reynolds said some centres had had to wait four to six months.
Barnardos general manager of child and family services Mike Munnelly said: "The delays caused by the process have had significant impact on our business. We are losing valuable potential employees who lose patience with waiting and get work elsewhere".
Other agencies requiring police vetting are also reporting hold-ups, such as a group which works with adults with intellectual disabilities.
Sue Kobar, manager of the Personal Advocacy Trust, said she had four new staff waiting on police checks before they could start work in Auckland, Wanganui, Nelson and Southland. Staff were having to travel to other towns to fill the gaps.
Vetting was taking a minimum of eight weeks, often longer.
Apii Aniterea, a 29-year-old final-year teaching student who has worked at Bright Sparks in Auckland since August 2012, filed her application for a police check last week to make sure it comes through before her current three-year clearance expires this August.
Police Acting Assistant Commissioner Dave Trappitt said the vetting service was being boosted from 16 fulltime-equivalent staff to 25 by next month to cope with the workload. Total vetting requests increased in each of the last three years from 424,907 in 2012 to an expected 530,000 this year.
Agencies have also struggled to get onto the police website and Mr Trappitt said it had been down for several hours on June 15 "to place into the production lines enhancements ready for safety checking under the Vulnerable Children Act".
High demand for the service may also reflect people getting in before a planned $7 vetting fee. A bill allowing police to charge for the service is due back in Parliament from a select committee today.
Police checks required
• July 1, 2015: All new workers in state-funded jobs who may be alone with, or have primary responsibility for, children ("core workers").
• July 1, 2016: All other new workers in state-funded jobs who work with children ("non-core workers").
• July 1, 2018: All existing core workers (180,000).
• July 1, 2019: All existing non-core workers (100,000).
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