Chinese researchers are breeding and selling two strains of Jackson Laboratory’s famous mice in violation of their contract, according to a federal lawsuit filed by the lab.

Jackson Laboratory of Bar Harbor, the world’s largest breeder of mice for medical research, filed a complaint Sept. 18 with the U.S. District Court for the District of Maine seeking to force arbitration between the lab and various arms of Nanjing University, which the lab said is selling offspring of Jackson mice at cut-rate prices.

The suit said Jackson Lab has produced more than 8,000 strains of genetically modified mice. At least 141 descendents of two strains of mice sold to the Chinese university for research only are in dispute.

“Any purchaser of a breeding pair of mice from Jackson is, theoretically, in possession of all that is required to start his or her own colony of mice for re-sale in competition with Jackson,” the lab’s suit said. “Jackson is clear with purchasers of its mice: They cannot breed and re-sell or distribute for sale any progeny of JAX mice.”

Verrill Dana in Portland and Wolf, Greenfield & Sacks in Boston represent Jackson Lab. “Jackson at this time does not want to comment on the nature of the lawsuit,” attorney Chelsea Loughren said Wednesday.

The dispute involves mice strains sold to the Chinese university from 2002 to 2014.

The complaint said Jackson Lab has repeatedly attempted to resolve the dispute, including with a March 31, 2016, cease-and-desist letter. On April 6, 2016, Jing Zhao, chief of the animal facility at a branch of Nanjing University, responded by saying his organization had removed all Jackson Lab offspring from its web pages and had stopped selling them. Jackson Lab disputes that assertion.