Traces of cocaine were found by police in a baby changing area during spot checks of pubs and bars.
Checks were carried out by North Wales Police over the weekend at 15 premises in the lead up to the Christmas period.
The tests involved using specialist drug swipe kits on surfaces in toilet areas.
Ten of the 15 premises returned positive results for traces of cocaine, including a baby changing area at one of the locations.
Police will be conducting further visits across the area over the coming weeks.
Advice has now been issued to licensees about how to report any concerns they have going forward.
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Sergeant Simon Barlow, of the neighbourhood policing team thanked the licensees for their “ongoing support”.
“It is concerning to find evidence of cocaine use in the restrooms of these premises and we are committed to working with partners to eradicate this,” he said.
“We will be conducting more visits across the district in coming weeks and have applied for funding to provide drug wipe test kits and anti-drug deterrent sprays to licensed premises.
“I would encourage anyone with information about drugs in their local area to report it to police or anonymously via CrimeStoppers.”