The National Football League's Washington Redskins failed to convince a U.S. judge to reinstate six trademark registrations canceled last year for being offensive to Native Americans.

A federal judge in Alexandria, Virginia, said on Wednesday that he agreed with the U.S. Patent and Trademark Office that the trademarks might disparage Native Americans and that the law allowing for cancellation did not violate free speech rights of the U.S. Constitution.

The team did not immediately have a comment on the decision.

The Redskins had filed a lawsuit last August against five Native Americans who had convinced the trademark agency to void the registrations in June 2014. The agency said a substantial number of Native Americans found the trademarks offensive.

The tribunal's decision put more pressure on the Washington club to change its name following decades of criticism by Native Americans, who say it is a slur.

A canceled trademark deprives the club of the ability to use the federal trademark symbol and block import and sale of counterfeit Redskins goods. However, the team can still use the "Redskins" name.

(Reporting by Andrew Chung)