NBA Commissioner Adam Silver said on Thursday he "couldn't disagree more" with remarks made by the head of the players union that the league's salary cap is unjust and un-American.

Silver also bristled at National Basketball Players Association Executive Director Michele Roberts' indication that she plans to ask for much more than the current 50-50 split of basketball-related income in the next contract with the league.

The NBA and some other professional leagues use salary caps to control costs incurred by individual teams and level the playing field among owners inclined to spend freely and those inclined to spend less.

Silver said the salary cap, which has been a part of the NBA's labor agreement since 1982, "has served as a foundation for the growth of the league and has enabled NBA players to become the highest paid professional athletes in the world."

"We couldn't disagree more with these statements," Silver, who succeeded David Stern as the NBA's top official in February, said in a statement responding to the comments by Roberts.

"The NBA's success is based on the collective efforts and investments of all of the team owners, the thousands of employees at our teams and arenas, and our extraordinarily talented players," he added.

"No single group could accomplish this on its own. Nor is there anything unusual or 'un-American' in a unionized industry to have a collective system for paying employees - in fact, that's the norm."

Roberts, elected in July as the first female union chief in major North American sports, made her remarks to ESPN The Magazine.

"Why don't we have the owners play half the games?" Roberts said. "There would be no money if not for the players. Let's call it what it is. There. Would. Be. No. Money.

"Thirty more owners can come in, and nothing will change. These guys (the players) go? The game will change. So let's stop pretending."

The NBA's nine-year, $24 billion TV deal is set to begin in 2016, and the players can opt out of the league's collective bargaining agreement after the 2016-17 season.

Roberts said the salary cap is "incredibly un-American. My DNA is offended by it." Roberts also said she was troubled by the league's rookie wage scale and its maximum contracts for top players.