Pearce behaviour unacceptable - Robinson

Sydney Roosters coach Trent Robinson has labelled Mitchell Pearce's behaviour as "unacceptable" after footage of him engaged in lewd behaviour involving a dog was made public on Wednesday.

The footage, which is said to have been recorded at an Australia Day party, showed a drunken Pearce simulating a sexual act with the animal.

The 26-year-old was stood down from training by the NRL club on Thursday and Robinson slammed the behaviour in a short statement.

"We at the Sydney Roosters have found that Mitchell's behaviour is unacceptable," Robinson said.

"And that's why he has been stood down until this matter has been resolved.

"We will go through that with the NRL."

Pearce is a key player for the Roosters and has also represented New South Wales in State of Origin.

He was fined $20,000 by the Sydney side in 2014 following an incident on a night out.