All life on Earth could be destroyed by genetically modified bacteria, a scientist has told the Royal Commission on Genetic Modification.
Four scientists gave evidence for the Green Party at the hearing this week via video link from the United States.
Soil ecologist Elaine Ingham spoke about a plant-killing GM bacteria that her Oregon State University research team prevented from being released into the environment.
Dr Ingham said the alcohol-producing bacteria had been approved for field trials when her team discovered its lethal effects.
She believed the widespread plant deaths caused by the bacteria would in turn affect all life on Earth.
The GM klebsiella planticola produced alcohol from post-harvest crop residue. The leftover organic sludge, containing the bacteria, would be returned to fields as fertiliser.
Dr Ingham said she had independently tested the bacteria on plants, which the regulatory authority had failed to do.
"After seven days, all wheat plants turned into slime."
This example showed the need for better risk assessment of ecological impact.
Green Party co-leader Jeanette Fitzsimons said the risks of GM organisms to the environment were currently unknown. Outdoor field trials of GM crops should never be allowed under these circumstances.