Pittsburgh, Pennsylvania - Pittsburgh Steelers safety Damontae Kazee has been suspended without pay for the rest of the season by the NFL for what the league called "repeated violations of player safety rules."

Kazee was ejected during the Steelers' 13-30 loss to the Indianapolis Colts on Saturday for a violent hit that knocked out receiver Michael Pittman.

NFL Vice President of Football Operations Jon Runyan said that repeated offenses from Kazee had led to the suspension which will see the player miss the rest of the regular season plus the play-offs, should the Steelers (7-7) qualify.

Kazee had already been fined five times this season for "unnecessary roughness" charges.

"When players violate the rules intended to protect player safety on a repeated basis, and particularly when the violations carry with them a significant risk of injury to an opposing player, it is appropriate to impose substantially greater penalties," Runyan wrote in a letter to Kazee, published by the league.

Runyan said Kazee's challenge, where he flew helmet-first high into his opponent at high speed, was a clear example of a flagrant breach of the rules.

"The video of the play shows that you delivered a forcible blow to the head/neck area of Colts' receiver Michael Pittman Jr., who was in a defenseless posture," he said.

"You had an unobstructed path to your opponent and the illegal contact could have been avoided. Your actions were flagrant, and as a result, you were disqualified from the game."

Steelers head coach Mike Tomlin had earlier defended Kazee after criticism of the hit.

"The target was low and both guys were going. It was just unfortunate. I know he is not a dirty player. He doesn’t aspire to do some of the things that came to light under those circumstances," he said.

"Sometimes it’s just professional football today and how difficult it is to operate, but the National Football League is really clear."

"They put a 100 % of the onus on the defender in those circumstances. It’s unfortunate, but we understand it," he said.

Kazee can appeal the suspension.