Scientific testing on behalf of Greenpeace Australia found Monsanto's "Roundup Ready" canola strain, which is resistant to some herbicides, had contaminated hives near Bannockburn owned by Edmonds Honey.

Victoria lifted a moratorium on growing GM canola in November 2007 after being advised it could be kept separate from non-GM crops.

Greenpeace spokeswoman Louise Sales said the contamination meant people were being denied choice: anyone buying honey from the affected hive could be eating GM food without knowing it.

She said it showed GM canola was "uncontrollable". "We're calling on the Federal Government to keep its election promise — basically not to release GM canola into the environment unless it was produced safe 'beyond reasonable doubt'. We don't believe it stands up to that test," Ms Sales said.

The health effects of GM canola remains contentious, though it is regarded as safe for consumption by the Commonwealth Office of the Gene Technology Regulator and the Australian Academy of Science.

Local farmers and Melbourne restaurateur Dure Dara joined a protest against the spread of GM material into neighbouring crops. The beekeeper affected by the contamination, John Edmonds, was less worried. He was concerned it could affect sales and said labelling should be improved. But he said beekeepers had been using GM cotton for years without negative health impacts.

A spokeswoman for the Federal Government said the health risks of GM canola had been extensively investigated and found not to differ from non-GM canola. GM labelling standards were being reviewed, with a report due mid-next year.

The State Government said the potential impact of GM canola on bee-keepers was considered in a review before the state moratorium was lifted.

Mr Edmonds said he would report the campaigners to police for removing and testing his honey frames.