NEW YORK (AFP) - A Kansas wheat farmer has sued Monsanto after news of the discovery of unapproved genetically modified wheat on an Oregon farm, alleging harm from falling wheat prices.

The farmer, Mr Ernest Barnes, lodged a civil lawsuit in a US federal court against Monsanto on Monday, alleging "gross negligence" and seeking compensation for damages, according to the suit.

"The case may be the first of many Monsanto faces over alleged wheat contamination," said the legal firm representing the farmer, Susman Godfrey, in a statement.

Mr Barnes is seeking compensation for damages "in excess of $100,000 (S$125,300)," the court document said.

Because of the discovery of Monsanto's genetically modified wheat, "farmers are now facing sharply declining prices and outright bans on the importation of their wheat in foreign countries," the complaint said.

While wheat futures prices fell immediately after US officials announced the discovery last Wednesday, they have since rebounded.

Wheat closed at US$7.09 a bushel Tuesday, compared with about US$6.93 a week ago.

Following the announcement last week, Japan suspended part of its US wheat imports as did South Korean millers, while the European Union said it would test wheat imported from the United States before allowing it to be sold.