SAO PAULO (Reuters) - Brazilian cotton producers in the state of Mato Grosso on Thursday sued Bayer AG (BAYGn.DE), seeking to cancel the chemical company’s patent protection for its Bollgard II RR Flex genetically modified cotton seed, according to a statement sent to Reuters.

The farmers, hoping to regain $151 million in royalty payments, claim the genetically modified seed does not constitute a de facto technological innovation, according to the statement issued by the Mato Grosso Cotton Producers Association (AMPA). The lawsuit also names Brazil’s national patents office as a defendant.

Mato Grosso soybean farmers used a similar argument when they sued in Brazil to cancel patent rights over the widely used Intacta RR2 PRO seed.

Sidney Pereira de Souza Jr., the attorney representing the farmers, confirmed that they were suing Bayer and the patent office, but would not comment further.

Valor Econômico newspaper was first to report on the farmers’ litigation plans on Thursday.

In a statement, Bayer said it had not been formally notified of any patent dispute related to the Bollgard II RR Flex technology. Bayer noted that this cotton seed technology was quickly adopted by Brazilian cotton growers, and was the most used in Mato Grosso.

AMPA said it will request a refund of $151 million worth of royalties that Mato Grosso farmers have already paid for use of the technology.

“If the patent cancellation request is granted, aside from getting the refund, the cotton farmers will save $240 per hectare in the coming harvests,” the statement said alluding to the royalties related to the seed.