Rogue websites are advertising fake premium rate numbers claiming to be phone lines used by the Royal Society for the Prevention of Cruelty to Animals (RSPCA).
The premium rate 0844 numbers give a false impression that they're affiliated with the charity and will rack up a heavy bill for the caller and," Action Fraud warned Wednesday (8 November).
The RSPCA said when a member of the public dials the fake number they will be charged a premium rate and then diverted to the National Control Centre helpdesk.
This means that in many cases the caller would not be immediately aware they had been scammed.
The charity checked Google and found eight different scam websites with the incorrect 0844 premium rate numbers within the first 10 pages of Google results.
"The amount of sites out there advertising incorrect contact numbers for our charity is very worrying," said RSPCA's head of education Dave Allen.
"We're urging people to watch out for websites with fake numbers and information that doesn't sound quite right," he continued.
"Some of the sites can be quite convincing with unauthorised feeds from our official Twitter and Facebook page which makes them look all the more real".
"Unfortunately it can be difficult to get these sites shut down, but we've been trying to solve this issue by reporting the problem to Google so that the sites aren't ranked highly in searches.
"We've also lodged a complaint to the UK's communications regulator Ofcom and now we're trying to raise awareness of this scam with the general public."
"Not only can these numbers leave people with a hefty phone bill, but it also means members of the public may be put off contacting us when an animal is in desperate need of care."
The correct number to report 24-hour cruelty to the RSPCA is 0300 1234 999. The call will cost the same as any call to a UK landline number.
It's not the first time that online fraudsters have used animals as a lure for scams. In April 2016, fake advertisements for puppies and kittens were uploaded online using stolen photos.
The fraudsters would caught asking for advanced payments to cover courier charges, shipping fees or vet bills for pets placed outside of the UK – but, when paid, the animal would never arrive.