The Ministry for Primary Industries (MPI) has confirmed a report that New Zealand was warned by the United States after exporting faeces-contaminated meat there in 2011 and 2012.
Deputy director-general of standards Scott Gallacher says 38 tonnes of meat was rejected for falling short of America's zero tolerance standard.
Mr Gallacher says after the ministry was notified by the US Department of Agriculture of the rejections it reviewed meat premises and found no systemic failings.
The ministry says last year New Zealand exported 190,000 tonnes of meat to the US and since the incidents in 2011-12 there have been no further rejections.
Robustness of inspection system questioned
The confirmation of the rejection comes as the union representing meat industry workers and the Green and Labour party's agricultural spokespeople are questioning the robustness of a new meat inspection system.
Meat companies at some plants are permitted to do some of their own meat inspections - replacing the independent inspectors working for AsureQuality.
MPI says none of the faeces-contaminated meat came from plants where companies did their own testing.
But critics, such as Public Service Association national secretary Richard Wagstaff, suggest the new system is leading to slipping standards. Mr Wagstaff says the union wasn't aware of the US warning until it was reported by a magazine this month.
AsureQuality has referred media enquiries to the ministry.