BUFFALO, N.Y. — The NHL said Tuesday it is investigating allegations Calgary Flames coach Bill Peters directed racial slurs toward Akim Aliu when he and the Nigerian-born player were in the minors a decade ago.

The NHL called the alleged behavior “repugnant and unacceptable.” The league added it will have no further comment until it looks into what happened more thoroughly.

Aliu tweeted Monday that Peters “dropped the N bomb several times towards me in the dressing room in my rookie year because he didn’t like my choice of music.” Aliu said he “rebelled against him,” and Peters responded by asking Chicago Blackhawks executives John McDonough and Stan Bowman to send Aliu to a lower minor league level.

Akim Aliu of the Calgary Flames during a game against the Anaheim Ducks on April 7, 2012. Gerry Thomas / NHLI via Getty Images file

The tweet did not name Peters specifically, but referred to a “protege” of fired Toronto coach Mike Babcock’s who is now in Calgary. Babcock has been a mentor to Peters since Babcock coached him in college.

Flames general manager Brad Treliving said the team is investigating the allegations Aliu raised during Calgary’s overtime loss at Pittsburgh. Peters was not made available following Monday night’s game.

“I haven’t had the chance to sit down with Bill or our people internally to talk about this and get to the bottom of it,” Treliving said. “We take these matters very, very seriously.”

The Blackhawks issued a statement saying nothing had previously been brought to their attention regarding Peters and Aliu before Monday. The team added it had no effect on any player personnel decisions involving Aliu.

Email and voice messages left with Aliu have not been returned to The Associated Press. The Flames were scheduled to practice Tuesday in Buffalo, where they close a four-game road trip Wednesday night.

The timing of the allegations come with the Flames slumping. They’re 1-5-2 in their past eight a year after Calgary won a franchise-record 50 games in Peters’ first season as coach.

Peters was hired by Calgary after spending four seasons coaching the Carolina Hurricanes. The 54-year-old made the jump to Rockford after leading the Western Hockey League Spokane Chiefs to a Memorial Cup championship in 2008.

Aliu played under Peters during the 2008-09 and 2009-10 seasons. He was demoted to the Toledo Walleye of the ECHL during the 2009-10 season. Aliu, who was born in Africa but raised in Ukraine and Canada, later played seven NHL games over two seasons with Calgary. The 30-year-old Aliu has had a transient career since being selected by Chicago in the second round of the 2007 draft.

He’s not playing this season after appearing in 14 games with Orlando of the East Coast Hockey League last year. The Solar Bears were Aliu’s 11th team over a six-year span, which included stops in Russia, Sweden and Slovakia.

Aliu’s tweet was prompted after reports surfaced of how poorly Babcock dealt with his players in Toronto. Forward Mitch Marner confirmed that during his rookie season Babcock asked him to rank Maple Leafs players in order of hardest to least-hardest working. Babcock then shared Marner’s list with numerous players.