Police have arrested three doorstaff in Stockport as part of a crackdown on unlicensed workers.
The Security Industry Authority (SIA) and police raided venues in Stockport and Reddish in Greater Manchester last weekend and issued warnings to a further 13 doorstaff for not displaying their badges.
All doorstaff must complete SIA endorsed training and exams before they can apply for a licence. The licence must be displayed when on duty.
Chief Inspector Stuart Barton, of Greater Manchester Police, said: "Having illegal supervisors on duty puts innocent people at risk. The public can rest assured that we will be making future visits to all premises to ensure they are safe places to visit."
Lucia Howland, SIA head of investigation, said: "The visit on Friday is part of an ongoing operation and I would like to thank our partners at Greater Manchester Police for tackling this area so proactively.
"Working without a SIA licence and deploying unlicensed operatives, is an offence under the Private Security Industry Act 2001 and licensees risk having their premises closed."