BOCA RATON, Fla. -- The NHL won't comment on an NFL executive's recent acknowledgment the brain disease CTE can be linked to football because it's not "necessary or appropriate" and the two sports are different, hockey's commissioner said Wednesday.

When asked at the annual general managers meeting to comment on the NFL's admission, Gary Bettman stuck to his position that the league isn't going to get into a public debate on the issue.

"Well, first of all, I don't feel that it's either necessary or appropriate for me to comment on what the NFL either says or does," Bettman said. "Secondly, I think it's fairly clear that playing hockey isn't the same as playing football."

Jeff Miller, the NFL's senior vice-president for health and safety, made headlines Monday when he told a U.S. congressional committee's roundtable discussion about concussions that brain research on former NFL players "certainly" shows a link between football and CTE.

NFL officials have long denied proof of a connection between playing in the NFL and the condition called chronic traumatic encephalopathy.

CTE is tied to repeated brain trauma and associated with symptoms such as memory loss, depression and progressive dementia.

Critics of the NFL's proposed US$1-billion plan to settle concussion claims call Miller's sudden acknowledgment of a football-CTE connection a game changer.

The settlement is being appealed by players concerned that it excludes future cases of CTE -- what they consider "the signature disease of football."

The NHL is also facing legal action over concussions.

More than 100 players have joined a class-action lawsuit against the league, alleging it had the resources to better prevent head trauma, failed to properly warn players of such risks and promoted violent play that led to their injuries.

The case, which was consolidated from several similar complaints in August 2014, has inched through the federal court system in Minnesota since then with no resolution expected soon.

The plaintiffs' primary request is medical monitoring for the roughly 4,800 living former players, plus additional unspecified relief. There is no dollar figure on the lawsuit, but the NFL's pending $1 billion concussion settlement with retired players could provide a benchmark.

Bettman, who was deposed for testimony last July, has said the lawsuit is "without merit." The league's first attempt to dismiss the claims was denied last year by U.S. District Judge Susan Richard Nelson. There is another pending motion for dismissal, based on an argument that the issues should be addressed through collectively bargained arbitration instead of court.