The housing charity Shelter has placed adverts on social networking site Facebook that target the supporters of other charities to ask them to make donations.
The adverts appear on the screens of users who have registered as supporters of charities such as Oxfam and the NSPCC. One such advert says: "Donate to Shelter. As an Oxfam supporter, have you thought about donating and helping us to secure a safe home for those vulnerable to homelessness in the UK?"
Shelter has used Facebook's targeted advertising system to ensure its adverts are shown to people who have shown an interest in other charities on the site.
A spokeswoman for Shelter said the charity was in the early stages of testing Facebook adverts. She said its targeting of potential donors was based on the other charities they supported, but also on their gender and interests.
"We're looking at different ways of using Facebook in a fundraising capacity," she said. "If you're a supporter of other charities, you might be likely to become a Shelter supporter, so Facebook users who have registered as fans of charities could be a good group to target with our adverts."