Swiss biotech giant Syngenta has announced that its US subsidiary Syngenta Seeds has filed a lawsuit against Monsanto, accusing its US rival of having a monopoly on biotechnology corn seed in the US.

The move follows an announcement by Monsanto that it had expanded a breach-of-contract lawsuit against Syngenta and is now seeking damages and termination of the Roundup Ready soybean licence that Monsanto originally granted to Ciba-Geigy Corp, one of Syngenta’s corporate predecessors.

Syngenta’s lawsuit alleges that Monsanto has “engaged in a pattern of illegal and improper activities to maintain its monopoly in key corn traits in the US, including Monsanto’s attempts to prohibit Syngenta from competing with GA21, an established and proven glyphosate-tolerant corn trait”.

Syngenta said it plans to offer the GA21 technology through its NK brand, the Garst and Golden Harvest brands, and through licences with other seed companies for the 2005 growing season.

Monsanto’s original breach-of-contract lawsuit, filed on 10 May 2004, claims that Syngenta is limited by its licence from Monsanto to commercialising Roundup Ready soybeans under one product brand.

Monsanto also said one of its subsidiaries had initiated a patent infringement lawsuit in Illinois federal court to stop Syngenta Seeds from developing, using and selling herbicide-tolerant corn seed such as Monsanto’s GA21 Roundup Ready corn product.