Callous thieves are stealing bags of valuables intended for the British Heart Foundation from outside homes in Balham.
The crooks are either sneaking down roads picking up bags, or knocking on doors masquerading as collectors.
Charity workers said house collections is a vital source of income and accused the thieves of stealing from the most vulnerable.
Elkie Woodbridge, spokesman at the charity, said: “These collectors are working for commercial gain, with none of the proceeds going to charity.
“All profits raised from goods donated to the British Heart Foundation shops go directly to fighting heart disease, which remains UK’s biggest killer.
“Stealing bags that have been left out for our charity is akin to robbing people with heart conditions of a better quality of life.”
The British Heart Foundation urges residents to be vigilant about who they give their goods to, and always ask for identification.
The charity collection vans now display the foundation logo, and residents can check whether collections are legitimate by contacting their local shop.
Residents are urged to call police if they see anything suspicious in their road, and are invited to drop their goods to their local shop in person.
In April charity shops in the borough reported an increase in shoplifting and pickpocketing during the recession.
The British Heart Foundation in Putney High Street saw £2,000 worth of new stock go missing over the Christmas period.
Rachael Jones, volunteer, said: “I understand the recession is on, but charity shops have still got to make money.”
At nearby Octavia Housing and Care, in Upper Richmond Road, a man even walked away with a chest of drawers.
Local British Heart Foundation shops urgently seek good quality clothing, handbags, shoes, accessories, DVDs, CDs, books, toys and bric-a-brac.
To find your nearest shop call 0844 412 5000 or visit bhf.org.uk/shops.
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