A van with the livery of an Abbey Wood-based hospice was reportedly seen trying to solicit bogus late night donations in Belvedere.
A group of six people allegedly got out and knocked on the door of a man who lives near the Greenwich and Bexley Community Hospice shop in Station Road at around 10.45pm on July 18.
The man, who wishes to remain anonymous, contacted the hospice with his concerns, which included that one of the callers had an ID badge and claimed to be from them.
Hospice chief executive Katie Heaps says none of their four box top Luton vans is ever used to solicit door-to-door donations.
She said: "It’s not just that they are using the hospice’s name without say-so but they are putting vulnerable people at risk in the community.
"If people see what looks like a hospice van driving round late at night then it’s definitely not one of ours and it’s worth phoning the police."
If you see anything suspicious, or have more information on this incident, call the police on 101 or Crimestoppers anonymously on 0800 555 111.