Tamara Mellon is taking issue with Jimmy Choo, the footwear and accessories label that she co-founded in 1996, and which she left in 2011.

On Monday, the designer began the first step in what may become a formal lawsuit against her former brand, sending a cease and desist letter to Pierre Denis, the company’s chief executive officer, that alleged “unlawful behavior” and conduct in breach of the European Union antitrust law.

The official letter, sent via Mellon’s lawyer at Olswang LLC, and obtained by WWD from a source and confirmed by Mellon’s representatives, states that Jimmy Choo harmed Mellon’s business by asking Italian factories to refuse to work with her brand. “Jimmy Choo has engaged in a course of conduct aimed at impairing our clients’ business by restricting its ability to source production capacity from the key suppliers to manufacture luxury leather products, including shoes, bags and accessories,” the letter reads.

The letter goes on to cite specific instances of the alleged behavior, including a meeting held by the company on June 10, 2013, between two Jimmy Choo employees and seven representatives from “key suppliers.”

“Mr. [Stefano] Savoldi [senior vice president, supply chain at Jimmy Choo Ltd.] said that there was concern at the London headquarters of Jimmy Choo regarding our clients’ ability to benefit from the same network of manufacturers and suppliers at Jimmy Choo,” the letter states. “Mr. Savoldi made it clear that Jimmy Choo did not want their suppliers working with our clients. The key suppliers present at the meeting all worked with Jimmy Choo and would have understood this to refer to them. It would have been plain to each of the key suppliers present at the meeting that Mr. Savoldi was putting pressure on them not to work with the clients.”

The letter further notes that Jimmy Choo has gone on to approach individual key suppliers directly and “put pressure on them not to do business with our clients. “We understand that in or around May 2014, Jimmy Choo entered into contractual arrangements with a number of the key suppliers,” it states. “These contracts included a side letter in Italian which required the recipient to agree that, for the duration of their agreement with Jimmy Choo, they would not produce anything nor cooperate directly or indirectly, through a third person, and/or through other companies, authorities, for or with Tamara Mellon and/or the Tamara Mellon brand including any brand used for the distribution of her products.”

Mellon’s lawyers persist in contending that these “side letters” put pressure on many Italian factories, resulting in Mellon’s inability to secure suitable production, and are an infringement of Article 101(1) of the Treaty on the Functioning of the European Union, which “prohibits agreements and concerted practices between undertakings that have the object or appreciable effect of preventing, restricting or distorting competition in the EU and in particular those which restrict sources of supply.”

According to Jimmy Choo’s initial public offering prospectus — the company has been listed on the London Stock Exchange since 2014 — it works with 28 specialist suppliers in Italy’s Tuscany and Veneto region, while more than 100 suppliers operate there.

A spokesman for Jimmy Choo said in a statement: “We have received a letter which is being evaluated. Our initial assessment is that the complaint has no merit and will be vigorously contested,” the statement read. “We plan to make no further comment until the process is completed.”

The letter concludes by stating: “Our clients’ priority is to minimize the damage caused to their business by Jimmy Choo’s unlawful behavior. We therefore require that you withdraw in writing the side letter and provide written assurances to each of the suppliers concerned that they are free to contract with our clients.” A source close to the case noted that the letter is a “prelude to a formal lawsuit.”

In the meantime, Mellon’s lawyers have also sent their own letter to nine Italian factories stating the illegal nature of the alleged “side letters.”