Cronulla chairman Barry Pierce and his board will investigate a fight between two Sharks players at Thursday's training session.

Forward Hutch Maiava was stood down indefinitely by the club after an altercation with lower grade player Jacob Selmes which resulted in Selmes requiring 20 stitches to his face.

Sharks coach Stuart Raper will front the media on Friday morning to explain how the two came to blows at a weights session.

"Hutch reacted physically, Jacob's had a few stitches," club spokesman Rob Willis said.

"They're saying 20 (stitches), I'm not sure it's that many but he had some stitches in his face.

New Zealander Maiava, a 120kg giant, made 24 first-grade appearances for the Sharks this year while Selmes is yet to play first-grade but captained Cronulla's Jersey Flegg side in its finals campaign this season.

In a statement, Sharks coach Stuart Raper, who was not present at the weights session, said he was surprised by the incident.

"I'm obviously very disappointed, as well as very surprised with what happened," he said.

The statement said club chairman Barry Pierce and his board would investigate the matter further.

"From the information we have received so far it appears Hutch was the aggressor, which is the reason why he has been stood down pending further investigation."

Willis said he did not know what had caused the altercation.

He said players were aware of tensions in Cronulla following last weekend's racially-motivated violence, but he doubted the incident had stemmed from that.

Raper was on Thursday night planning to speak with club chief executive Steve Rogers, who is holidaying in Italy and was unaware of the incident when contacted by AAP.

An NRL spokesman said it would remain a club matter if the incident took place at a private training session.

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