Leading producers of high fructose corn syrup, including Archer Daniels Midland and Cargill, have launched legal action against The Sugar Association over false marketing claims.

The group of companies, which also includes Ingredion and Tate & Lyle Ingredient Americas and are all members of The Corn Refiners Association, have filed the lawsuit in the US as a counter-claim to one already filed against them by the Sugar Association.

They accuse the Sugar Association of “preying on consumer fears” by attempting to vilify high fructose corn syrup (HFCS).

It is the latest round in an increasingly bitter battle over the definition of high fructose corn syrup (HFCS), used widely as a sweetener in foods and soft drinks.

Adam Fox, of Squire Sanders, the co-lead counsel for the Sugar Association, accused HFCS producers of trying to “muddy the issues” with their latest counterclaim. “The evidence plainly shows that sugar and HFCS are not the same. They are molecularly different,” he said.

Last month, a court in Los Angeles ruled that ADM, Cargill, Tate & Lyle and Corn Products International must answer to claims that they misleadingly advertised HFCS as “natural corn sugar”. In May this year, the Food & Drug Administration ruled out the use of the term ‘sugar’ to describe HFCS.

Since 1970, sugar consumption in the US has fallen by 40%, while consumption of HFCS has increased by 1,000%, according to the Sugar Association trade body.

The current dispute between the sugar and HFCS producers stems back to April 2011, when the Western Sugar Cooperative filed a lawsuit against ADM over the firm’s alleged attempts to equate the two ingredients.