Over 7,000 suspected TV pirates will receive a police letter warning them that they are being watched - and could be jailed.
The letters, which are being posted this week, will target those suspected of using devices, such as IPTV and Kodi boxes, to illegally stream premium channels.
If the cease and desist letter is ignored, it warns that those who continue to break the law could face up to five years in prison.
"These notices are a direct and alarming wake up call for people using illegal streams," warned Kieron Sharp, CEO of the Federation Against Copyright Theft (FACT).
"If you use illegal streaming services you are accountable for your actions and you will be pursued. This is not a grey area and it is not worth the risk."
Lancashire Constabulary's Cyber Crime Unit is behind the latest letters.
Similar letters from other forces have been sent to addresses across the UK.
The notice, one of the first of its kind aimed at consumers of illegal streaming services, makes clear that the force will monitor subscribers’ behaviour and an investigation will be launched if the email is ignored
This action is part of an ongoing investigation designed to crackdown on illegal streaming and those profiting from it, and follows similar letters sent out earlier this year by police in Norfolk and Suffolk.
Olivia Dodding from Lancashire Police Cyber Crime Unit said: “People who subscribe to these services might not realise that they are illegal, but the fact is they are, and we believe that the people who sell them know that.
“What may cost you a relatively small one-off fee, actually results in television producers and sports broadcasters losing millions of pounds which affects their ability to make and show sports events and entertainments series, which many of us enjoy watching.
“Anyone who subscribes to IPTV or any other illegal streaming service should stop now to avoid facing prosecutions themselves.”
