Residents of the Borough and Bankside area have been warned to be alert to fake 'sorry we missed you' cards purporting to come from a courier service.
Earlier this week homes in several blocks in the area received cards carrying the logo of the Deposit Protection Service, a Government-authorised company which deals with landlords and lettings agents.
The cards asked recipients to call a premium-rate number to arrange redelivery of a parcel.
One resident who called the number said that "... they try to get as many personal details out of you as possible with the potential aim of finding out when you are in or out".
Pictures of the fake cards were circulated by Sgt David Hunt of Cathedrals ward safer neighbourhood team who tweets as @MPSCathedralSgt.
"If people get a card like this they are urged not to call the number unless they believe it to be legitimate," said a Southwark Police spokesman.
"This card is of very poor quality and appeared to be scanned or photocopied.
"If people expecting a parcel they will normally be notified which company will deliver it so they should keep an eye out for suspicious cards like these.
"If in doubt contact your local police team for advice."
A DPS spokeswoman told us: "The Deposit Protection Service never delivers any kind of parcel to anyone so this kind of card will always be a fake."
"If you're at all unsure about anything you've received that claims to be from us, give us a call and we'll confirm whether it's genuine – you can reach us on 0844 4727 000 – which is not a premium rate number."