A chain of fitness clubs accused of using Steve Nash's name without permission is going on the offensive and suing the former basketball superstar's company for allegedly damaging its reputation.

​SNFW Fitness BC Ltd., which runs 21 gyms across British Columbia, has filed a counterclaim in B.C. Supreme Court, asserting that it retained the legal right to use what it calls the "Nash endorsement" after parting ways with its famous frontman in 2014.

"SNFW has and continues to suffer loss, damage and expense, including but not limited to damage to reputation and the cost of rebranding the SNFW business in the context of … Nash's public repudiation of the Nash endorsement," says the counter lawsuit, which was filed in late 2016.

Nash's company sues over name

Nash's Arizona-based company, B & L Holdings, filed a lawsuit against SNFW Fitness in October, accusing it of illegally using Nash's brand after his relationship with two business partners fell apart two years earlier.

Besides the fitness chain, defendants in the claim include Mark Mastrov, a part-owner of the NBA's Sacramento Kings, and Quebec businessman Leonard Schlemm.

None of the allegations have been proven in court and none of the parties named in the legal actions responded immediately to requests for comment.

There are 21 Steve Nash Fitness World locations in B.C. (Steve Nash Fitness World)

The original notice of civil claim filed by B & L Holdings says the company gave permission in 2006 for the unlimited use of Nash's name and image to a firm responsible for running a pair of Steve Nash Fitness Clubs.

The document says the legal agreement was transferred through several companies, precipitated in part by Mastrov's purchase of an ownership interest in the Sacramento Kings. NBA rules regulate the extent to which franchise owners can be in business with players, and Nash was with the Los Angeles Lakers at the time.

Nash, fitness chain split ways

The lawsuit claims that Nash has not received any compensation for the use of his name and personal brand since he sold his shares evenly to Mastrov and Schlemm in 2014.

In their response to the notice of civil claim, Mastrov and Schlemm say the company has the lawful and exclusive right by Nash to use his name, voice, signature, likeness and image within British Columbia.

The document alleges Nash knowingly sold his stake in the company and that the rights transferred in that sale included the ability to use the Nash endorsement.

It says B & L Holdings received $1,871,180 in exchange for Nash's shares.

Both sides are seeking unspecified damages and costs as part of the lawsuit.

Nash was twice named the NBA's most valuable player over his nearly two decades with the league, becoming the first Canadian to receive the award.