An organic farmer is suing his farming neighbour for allegedly contaminating his farm with genetically modified oilseed rape.

Steve Marsh, an organic farmer in Kojonup, Western Australia, is suing Michael Baxter for loss of income and damages totaling $AUS85,000 (£46,000).

Mr Marsh, who runs an organic oat and sheep farm, is claiming financial compensation after he lost organic certification for 70% of his farm when GM oilseed rape material found its way on to his farm in November 2010.

His farm, situated 160 miles south-east of Perth, had been certified by the National Association for Sustainable Agriculture Australia (NASAA). It operates with zero tolerance for GM material.

Mr Marsh claims GM oilseed rape blew about one mile over his boundary fence and contaminated his crops.

The landmark court case, which is due to last three weeks, began on Monday (10 February) in the West Australian Supreme Court. The outcome could set a precedent for a farmer’s right to grow GM crops in the country.

Mr Marsh’s lawyer Richard Niall told the court this had a devastating effect on Mr Marsh’s livelihood, The Australian newspaper reported.

“[Mr Baxter] failed to contain the genetically modified seeds, and they escaped on the wind on to the Marsh property — thousands of seeds were deposited on Eagle Rest,” he said.

“At the time he planted the canola, he knew … that GM seed would escape. It was plainly foreseeable.”

However, Mr Baxter’s lawyer told the court that he had swathed the crop and abided by the legal buffer zones, so therefore had no case to answer.

US biotech company Monsanto, the world’s largest producer of GM seeds, is understood to be supporting Mr Baxter’s defence.

The case, which has pitted two former childhood school friends against each other and divided the farming community, continues on Tuesday (11 February).