SYDNEY (AP) -- Australian police shut down the Sydney offices of environmental group Greenpeace on Thursday after its activists destroyed a genetically modified wheat crop at an experimental farm run by the government.

Police in Canberra, the Australian capital and the site of the experimental farm, said "an amount of property was seized as evidence" during the Sydney raid and it will undergo forensic analysis. No arrests were made.

Greenpeace activists, wearing mock hazard suits, scaled the fences of the experimental farm last Thursday and destroyed a crop of genetically modified wheat with brush cutters. The wheat has been altered to lower its glycemic index in an attempt to see if the grain could have health benefits such as improving blood glucose levels and lowering cholesterol.

Greenpeace says it took the drastic action because of concerns over health, cross-contamination and the secrecy surrounding experiments at the farm, which were to include the first human trials of the crop.

The Commonwealth Scientific and Industrial Research Organization, Australia's national science agency, says the experimental crop did not introduce any new genes to the plants and was safe for humans. It says it had already fed the genetically modified wheat to rats and pigs.

Greenpeace's head of campaigns, Steve Campbell, said the organization is "assisting the police with their inquires." However, Greenpeace will continue its campaign to put the spotlight on genetically modified wheat in Australia, he said.

"It's a really important issue for Australia, for our environment, for our future," Campbell said.

Copyright 2011 The AP.