Letterboxes are the new target for thieves hitting homes in Merton Park, stealing keys and valuables without even opening the door.
Merton Park safer neighbourhood team (SNT) has noted a spate of burglaries committed by individuals using long poles or similar devices to "fish" items from hallways through the letterbox.
PC Will Dauncey from Merton Park SNT said: “Sometimes house keys are taken so the thieves can gain entry to the house but not always.
"We've seen them take car keys left on shelves and just steal the vehicle.
"It's happening all over the ward, but mostly in the north of our area, along Dorset and Sheridan Road."
Police are appealing to residents to make sure valuables are not on display and to keep all windows closed, which are easily left accidentally open in summer.
Homeowners can guard against items being dragged back through letterboxes by fitting security flaps or cages which stop items being pulled back through the letterbox.
PC Dauncey said there are no leads yet as to who is behind the burglaries and added it is unlikely to be just one group.
"It has been hard to link the thefts as it is not always the same method used.
"Also they have not been restricted to one time of day - there have been burglaries both in the middle of the day and late at night," said PC Dauncey.
Plainclothed policemen have been patrolling the area in a bid to stop the crime wave, in addition to making door-to-door calls and advising residents on how to make their homes more secure.
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