The Newcastle Knights have reportedly launched an investigation after footage emerged of fullback Kalyn Ponga and teammate Kurt Mann being kicked out of a toilet cubicle.

A video has circulated on social media of Māori All Star Ponga, who is currently sidelined with concussion, and Mann leaving the toilet cubicle fully-clothed.

"Oh, that's a surprise," the security guard can be heard saying after spotting the footballer.

The four-second clip is captioned: "Ponga getting done in the toilet."

According to The Daily Telegraph, the Knights are seeking an explanation from Ponga.

However, Ponga's father Andre told the News Corp publication that the Newcastle duo were in the toilet together due to illness.

"He made an exciting house purchase Saturday and celebrated with a few mates drinking," he said.

"Sick in the toilet and his mate went in to help him."

Ponga has been sidelined since copping a high shot from Sydney Roosters forwards Matt Lodge during Newcastle's Round 19 clash, his third concussion in six weeks.

On Sunday afternoon, the 24-year-old confirmed to Triple M his season was over due to strict concussion protocols.

"I'd be sweet for the last round but doing no contact for the year, it probably would be a wise thing not to play the last round," Ponga said.

Kalyn Ponga playing for the Māori All-Stars against the Indigenous All-Stars in 2020. Photo / Getty Images

"My season's done. It's a bit weird. I feel OK now. At the start I felt a bit weird, headaches and whatnot, but I feel all right now.

"It's just hard. I feel OK. I feel fit. I want to play but I guess I'm just going through the protocols at the moment.

"It is tough. I feel sweet. There's nothing wrong with me.

"I can't feel anything but I just have to trust the process that's ahead of me."

Meanwhile, Mann is currently recovering from a quadriceps injury that has restricted him to 11 games this season.

Ponga has played 88 NRL games for the Knights since signing for the club in 2018, also representing Queensland in seven State of Origin fixtures. He was born in Western Australia to Kiwi parents but spent part of his youth in Aotearoa, even winning New Zealand's under-13 golf championship.

He signed a five-year contract with Newcastle earlier this season.