Australian police on Thursday raided the Sydney offices of Greenpeace over their destruction of an experimental crop of genetically modified wheat at a government research farm.
Police seized a number of items for forensic analysis from the activist group's headquarters after interviewing two "persons of interest" in the case.
"The search warrant was executed in relation to an alleged trespass and property damage at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Ginninderra Experiment Station in Canberra last week," police said.
Greenpeace campaigns chiefsaid officers "spent some hours" at the offices, adding that staff cooperated fully and no arrests were made.
"We had to stop everything that we were doing and speak with police and then go into cooperation mode," Campbell told AFP, declining to comment on what items had been seized.
"We're not going to take a backwards step in talking about this issue and our campaign to stop genetically modified wheat being released into the Australian environment," Campbell said.
Three Greenpeace activists broke into the GM wheat farm last Thursday and, armed with weed-trimmers, razed the experimental crop which had been modified to lower its glycaemic index and boost fibre.
Greenpeace says there are serious contamination issues with GM wheat and argues it has not been proven safe for human consumption, with major exporters including the European Union, Russia and Canada rejecting the crop.
The half-hectare CSIRO crop was intended for dough baking trials for feeding to rats and pigs, with an eye to human trials, though the agency would have to obtain a fresh licence to test the grain on people.