GE Free New Zealand is asking the Environmental Risk Management Authority (ERMA) to reassess its approval of AgResearch's experiments with genetically modified animals.
Last year, ERMA approved a 20-year proposal for AgResearch to continue its research programme with genetically modified cattle and other animals to produce therapeutic proteins in milk.
GE Free's latest call for a reassessment is based on an independent review of AgResearch's monitoring procedures by Canterbury University's Centre for Integrated Research in Biosafety.
The centre's director, Dr Jack Heinemann, says it peer-reviewed the monitoring programme AgResearch was required to do, which involves testing soil around the burial sites of genetically modified animals for signs of horizontal gene transfer.
Results of the soil tests Agresearch supplied to ERMA showed no evidence of modified genes from the animal carcases appearing in soil bacteria.
But Dr Heinemann says the centre's review shows AgResearch's monitoring programme was flawed and incapable of detecting horizontal gene transfer, even at very high levels.
Dr Heinemann says the sampling was also too limited to be meaningful as it ignored about 99% of soil bacteria and 100% of all other soil micro-organisms.
AgResearch's applied biotechnologies head, Dr Jimmy Suttie, says the monitoring programme was robust and denies the suggestion it was designed so that no evidence of gene transfer would be found.
ERMA says it will assess GE Free's application for a review to see whether there are grounds to reconsider its approval for the transgenic animal research.