Owners of missing dogs are being sent blackmail threats demanding £450 in bitcoin or their pet will be killed or sold.
The 'despicable' crime has been reported in a number of locations in Lancashire.
Now police are warning owners not to fall for the scam and to contact officers instead.
Lancashire Police say the fraudsters are targeting owners who have lost a dog and then shared an appeal for help finding the pet online.
Victims are usually contacted via text from an unknown number, LancsLive reports.
The fraudsters then say the victim has a limited amount of time - usually a day - to transfer bitcoin or the scammers will kill their pet.
In one example, officers were called at 2.56pm on March 31 by a woman in Longridge who had received threatening phone calls from a man claiming he had her lost lilac and tan French Bulldog Nelly. They said they would harm Nelly if she did not pay a ransom of £1,000 by 3pm that day.
Officers said in that case the man did not send any proof that he had Nelly.
The victim was then contacted the following day with a message stating, “I have your dog. It’s fine just scared. Send £450 in bitcoin to this bitcoin wallet or I will sell it or whatever.
"When you pay send your address and I’ll drop it off. I won’t contact you again or reply. This is a throwaway phone. Police can’t help. You have until end of Thursday.”
Police bosses said is not clear whether the phone call and the message came from the same individual.
Juliet Clark, of Lancashire Constabulary’s Cyber Crime Unit, said they take these offences, which are classed as blackmail, extremely seriously and if you receive one of these fraudulent messages, the advice is to not respond and call the police.
She said: “These despicable individuals play on the emotions of their victims when they are at their most vulnerable.
“As upsetting and tempting as it is to pay the ransom, this is scam. If people are contacted after losing a pet with similar messages, contact police on 101.”
Anybody with information about the whereabouts of Nelly is asked to call police on 101, quoting log 0934 of March 31, 2021.
