PORTLAND – Biotech company Monsanto has asked the state to suspend the use of its Quality Trademark Seal program for dairy products, saying that it misleads consumers about the superiority of milk that is free of bovine growth hormone.

In a letter to Attorney General Steven Rowe and Agriculture Commissioner Robert Spear, the St. Louis-based company said that milk from cows treated with its bovine growth hormone product, POSILAC 1 STEP, is “equivalent in all respects to other milk.” The product, known generically as rBST, is used to enhance milk production.

Products with the Quality Seal label are required to use only milk from farmers who provide affidavits that state the milk is believed to be from cows that are not given rBST. Monsanto, joined by the Biotechnology Association of Maine and three dairy farms, said the claims on those affidavits are impossible to substantiate.

The parties contend that the program gives consumers the false impression that milk from cows that have been given the hormone is associated with health risks.

They also argue that two major processors, Portland-based Oakhurst Diary and H.P. Hood, based in Chelsea, Mass., are engaging in unfair trade practices by using the labels. They have asked Rowe to initiate law enforcement proceedings against Oakhurst and Hood.

Deputy Agriculture Commissioner Ned Porter said Wednesday that his department is looking to Rowe’s office for advice on how to proceed.

“They have the legal expertise, and we’re hoping for some guidance,” Porter said.

Representatives from the attorney general’s office, Oakhurst and Hood who are authorized to discuss the issue were not available for comment when their offices were contacted Wednesday afternoon.

Oakhurst acknowledges on its Web site that the U.S. Food and Drug Administration has approved the use of products like Monsanto’s, but that concerns remain.