Manly have confirmed two members of their coaching staff had been involved in an incident outside the Orient Hotel in Sydney.
The Sea Eagles said on Thursday they will investigate the incident reportedly involving assistant coach Willie Peters and head of physical performance Dan Ferris.
"The Manly Warringah Sea Eagles have been made aware of an incident involving two members of our coaching staff yesterday evening," the NRL club said.
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"The club has commenced an internal review into the matter. We have notified the NRL integrity unit that we have commenced our review and will keep them fully informed."
Fairfax Media reported Peters and Ferris had to be separated by police on Wednesday night during a brawl outside the Orient Hotel in The Rocks.
NSW Police say two men, aged 38 and 31, had refused to make statements or assist police with their inquiries after the fight at 7pm.
"A criminal infringement notice was issued to a 38-year-old man for offensive behaviour," police said in a statement to AAP.