An organised gang of smartphone thieves is targeting nightclubs in Lincoln, Lincolnshire Police warns.
The force said up to four smartphones are reported stolen in the city every weekend.
In one particular case, 12 smartphones were stolen in one night, police said.
In most cases, the phones are stolen from handbags or from tables, while the owners are at the bar or restrooms.
PC Steve Parker said: “We do still have a real issue with the theft of mobile phones in Lincoln, particularly from the city’s nightclubs.
“We average three or four every weekend, either from handbags, or phones that have been left on tables while people go to the bar or use the toilets.
“We believe organised criminal gangs are targeting premises in Lincoln and we have examples where 12 smartphones have gone in one night,” he added.
Police are now urging smartphone owners to register their devices and take advantage of security apps to beat gangs of organised thieves.
Two phones stolen from the Lincoln area last month were registered, and officers in Lincolnshire were alerted when they were being used elsewhere in the country.
Officers were able to locate the phones and arrest the alleged offenders, who are suspected of thefts across the UK.
On Apple iPhones, owners can enable the Find my Phone tracking feature, while Android users can find a range of similar services available in their app store.
PC Parker added: “You need to be very careful with your smart phone when you are out for the evening – never leave it out on a table or in an unattended bag.
“Secondly, always register your phone’s IMEI number. To get it just dial *#06# on any handset and it will appear. Register this at www.immobilise.com.
“This means we can trace the handsets before they are sold on and leave the UK and hopefully make more arrests in this area,” he explained.