SPOT checks on pubs and clubs in Sheffield found a bar manager employing bouncers without a Security Industry Authority licence.
During the inspection last Friday nine venues were visited by licensing officers from South Yorkshire Police and an SIA investigator.
In one bar, the manager who employed door supervisors did not have the necessary SIA licence to do so.
It was also found the venue had no means of checking on staff working, such as a log book or signing in sheet.
An Improvement Notice was issued by the SIA.
Nigel Davies, SIA head of investigation, said: “This was an intelligence-led operation which successfully targeted non-compliance in this area.
“We will continue to work in partnership with South Yorkshire Police to clamp down on those willing to break the law.
“I remind those who manage or supervise door supervisors that they must themselves be licensed, and they can check our public register of licence holders to ensure their employees are working legally.”
Andrea Marsden, police licensing enforcement officer, said: “The operation carried out was another good example of partnership working between the police and SIA.
“Checks were carried out throughout the Sheffield area to ensure all door staff had the correct licences to carry out their duties in ensuring public safety at licensed premises.
“South Yorkshire Police intend to build on this good practice with the SIA and other agencies with an interest in the licensing trade.”