Rugby League: Shaun Johnson apologises after breaking NRL rule

New Zealand league star Shaun Johnson has apologised after being caught breaking a NRL rule at the weekend.

The Cronulla Sharks playmaker went off with a hamstring injury during his side's 29-6 defeat to the Brisbane Broncos, but was caught on camera using his phone as he sat dejected in the locker room.

NRL rules prevent players from using their mobile phones in the dressing rooms during a match, with the league having banned mobiles from dressing rooms in 2017 in an attempt to shut out any contact between players and gamblers.

Johnson put his hand up to acknowledge he made a mistake, but explained that he was simply calling his fiancee, netballer Kayla Cullen, to let her know about his injury.

"I just called her without thinking and spoke to her," he said. "It was a tough time and frustrating going through that on my own.

"I let her know I was OK and that's all there was to it. I put my hand up and I did muck up."

Johnson might have some good news regarding the phone saga, with the Sydney Morning Herald reporting that they "understand" the NRL may treat his dressing room gaffe favourably, and likely just slap the Kiwis half with a warning.

However, Johnson will still be sidelined regardless, with Sharks officials confirming Johnson will be out for a month due to the hamstring injury.

He should then be free to play for the Kiwis against Tonga on June 22.