Penrith coach Ivan Cleary is under investigation and could be fined for allegedly swearing at NRL referee Ashley Klein at halftime of the tense clash against Canberra on Sunday.

NRL360 alleged that in the tunnel at Panthers Stadium, Cleary said to Klein: “Ashley they’re f***ing lying all over us. You can’t let them. You’ve got to stop them.”

Penrith lost the game 30-18 and Cleary admitted in his post-match press conference that he approached the referees at halftime.

“I might’ve spoken to them, yeah, possibly. You can ask them. It was nothing untoward,” Cleary said.

NRL head of football Graham Annesley said it strictly prohibited coaches to approach referees during games.

“Our rules are very clear about referees being approached in the course of a game, so we’ll continue to get the information we need, we’re not under any time constraints, and then we’ll talk to the Panthers,” Annesley said.

Penrith have lost their past nine matches when Klein has been officiating, and 13 of the past 15.

Sydney Roosters coach Trent Robinson was fined $40,000 for comments made to referee Ben Cummins on Anzac Day in 2016.