Eastern european criminal gangs are targeting revellers at night spots in Windsor town centre snatching handbags, purses and even rings.
Police say they are running undercover operations at venues in Goswell Hill and other busy nightlife spots after a severe problem in June and July when 16-17 thefts took place every weekend.
PC Val De Haan, from the Windsor neighbourhood team, said special operations have been run, leading to a drop in August, but more will take place as crimes continue.
He said: "The big difference is they have been at nightclubs this year and we have had Romanian gangs, and others, coming into the town and picking on people with bags and mobile phones.
"We also had a woman who had a ring taken off her hand in a nightclub, but did not realise someone had taken it - they are pretty good."
He said a range of different tactics are being used during the day and night by gangs coming from Hertfordshire, west London and other areas.
Criminals are also pick-pocketing during the day and laying maps on tables at cafes to distract people before stealing mobile phones, handbags and purses.
A pick-pocketer stole a purse from the bag of a woman in the town centre on Saturday and a tourist had his wallet stolen in Peascod Street on Thursday.
'Confidence tricksters' were also out on Saturday running a 'find the ball' under a cup scam, while coach park arrivals are also being targeted.
PC De Haan said more undercover operations will take place at weekends and during the Paralympic Games.
He also warned revellers and day visitors to Windsor town centre to be on their guard.
"People need to be far more aware of things, more guarded and must be more aware of their security," he said.
Police are giving out free purse bells to women at Windsor Police Station in Alma Road to help alert them to pick-pocketers.
Call police on 101 or Crimestoppers anonymously on 0800 555111.
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