Spencer Leniu has admitted to using an offensive remark against Broncos star Ezra Mam in the NRL’s season-opening double-header in Las Vegas.

Leniu, who was playing his first game for his new club, lodged a guilty plea to a contrary conduct charge with the NRL judiciary on Thursday. He now faces a long suspension after admitting to calling his opponent a “monkey”, but insisted it wasn’t used in a racial nature.

“I want to apologise to Ezra and his family for using the word I did, and I am sincerely sorry to cause him such distress,” Leniu said in a Roosters statement.

“I’ve put my hand up and want to take ownership of this. I said the word, but I didn’t mean it in a racist way. Anyone who knows me knows that’s not who I am.”

Leniu had initially denied using a slur in post-game interviews after the Roosters’ 20-10 win over Broncos at Allegiant Stadium, telling Triple M the angry exchange with Brisbane players was “fun and games”.

He later had a confrontation with Brisbane stars including Kotoni Staggs and Pat Carrigan in the corridor of the Las Vegas hotel they were sharing in the early hours of the next morning. The incident was only verbal and not physical.

Mam was in tears after the game having lodged a formal complaint with the referee Adam Gee, but the NRL couldn’t detect audio of the incident.

Mam’s Brisbane teammates Billy Walters and Payne Haas had indicated they would testify against the Roosters star at the judiciary, which will now determine how long Leniu will be on the sidelines. The hearing will be held on Monday night after Leniu’s plea with James McLeod to represent the Roosters.