The PSA says allowing companies to do some of their own meat inspections could undermine New Zealand's meat standards.
The Ministry for Primary Industries says overseas markets have approved changes that will allow the processors to take over some of the work currently done by government meat inspectors, employed by AsureQuality.
The ministry says that would be limited to non health-related quality control. Meat inspectors will continue to do the food safety checks, with MPI vets overseeing the whole process.
The ministry says it's in line with the way New Zealand's trading partners are heading with their inspection services.
But the PSA, which represents meat inspectors, says there's an obvious conflict of interest in allowing meat inspections to be done in-house, and that was borne out in a trial done last year.
National secretary Richard Wagstaff says there's a suggestion that meat inspectors will continue to have oversight and manage food safety elements, but the union does not believe this.
"Meat companies in this trial excluded issues such as faecal contamination and wounds and bruises and a whole lot of other issues weren't seen to be food safety elements and they were handed over to untrained company workers", he says.
Mr Wagstaff says it's good to see that training is now required but it doesn't remove the conflict of interest because when a company is seeking to maximise through put and profit it would be very difficult for one of its employee to continually hold up the process and reject product.
He says the number of meat inspectors could drop significantly from the more than 800 currently employed.
The Meat Industry Association is expecting about six plants to start doing some of their own inspections this year.