bikies were involved in a Melbourne nightclub bashing that left five staff members needing treatment at a hospital.

Police are investigating whether bikies were involved in a Melbourne nightclub bashing that left five staff members needing treatment at a hospital.

Police say five men entered the premises of the Centrefold club in King Street in Melbourne's CBD sometime after 6am (AEDT) but the group was asked to leave as the bar was closing.

A fight broke out and several of the employees were assaulted.

"We're talking with witnesses and trying to see if a bikie gang was involved," a police spokeswoman said.

Five people were treated in hospital with minor injuries varying from cuts and bruises to a broken jaw.

In a separate incident, a man was found beaten unconscious outside the Men's Gallery club in Lonsdale Street on Sunday morning.

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