Stickers promoting a locksmith business are being used by burglars to mark homes in south-west London which are an "easy target", a council has warned.
Scouts carry out a reconnaissance and stick almost transparent stickers on front doors, Wandsworth Council said.
The stickers say "24/7 Locksmith" and contain a phone number, which does not exist and was never issued to anybody.
At least one burglary has been linked to the stickers and the council has advised residents to remove them.
Police officers believe the scout makes a visit during the day to check if anybody is home and at the time they also get an idea about the doors, windows and locks.
Councillor Jonathan Cook said: "There is growing evidence that some organised teams of burglars may be using this method to target homes in south London.
"We are therefore urging local residents to keep a very close eye out for these stickers and if they find one to remove it straight away."
Wandsworth Police said officers were pursuing several lines of inquiry.