Erma chairman Neil Walter said the quasi-judicial nature of the authority meant it was inappropriate to discuss the merits of the decision.
The decision was taken last week and made accessible on Erma's website with a password on Friday to many of those who made the 1500 submissions on the application.
"Unfortunately, it went out," he said of Friday's leak. An unknown person had broken confidence.
"I wouldn't say there was any sloppiness [from Erma]."
The recently lifted GM moratorium did not cover this type of field test application, which was allowed before and during the moratorium, Mr Walter said.
It was the 14th such decision Erma had made.
Mr Walter said he was concerned at some of the reasoning behind anti-trial protests and urged opponents to "come and see us".
- NZPA
Environmental Risk Management Authority:
Decision on field testing of GE onions
[PDF]
Herald Feature: Genetic Engineering
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