Victims of burglaries in Nelson may be unaware that their credit card details have been photographed.
Police say there have been five to six burglaries in the Richmond, Stoke and Nelson areas in the past week.
Area commander Inspector Steve Greally said the offenders either write down or photograph the credit card details and then use the information to buy things online. He said in each case nothing else appears to have been stolen.
"The offenders have gone into the addresses and either manually recorded the credit card details or they've taken a photograph - and that's including the number, the name, the expiry date and the three-digit code on the back of the card."
Mr Greally said the most common purchase is flights out of Nelson. He said some people have taken up to a month to realise their details have been stolen, and anyone who has been burgled recently should contact their bank.