Popular music website RnBXclusive.com has been closed down by the Serious Organised Crime Agency (Soca) and past users of the site have been warned that they risk facing criminal charges.
The Soca website warning reads: "If you have downloaded music using this website you may have committed a criminal offence which carries a maximum penalty of up to 10 years imprisonment and an unlimited fine under UK law."
Soca said that one individual behind the site has been arrested on charges of conspiracy to defraud.
The agency said it has the power to monitor and investigate users, whose IP address and location can be detected.
"You may be liable for prosecution and the fact that you have received this message does not preclude you from prosecution," the warning says.
"As a result of illegal downloads, young, emerging artists may have had their careers damaged. If you have illegally downloaded music you will have damaged the future of the music industry.
"Visit pro-music.org for a list of legal music sites on the web."
A Soca spokesman said: "Soca targets organised criminal enterprises profiting from the exploitation of the UK public and legitimate businesses. Much of the music offered for download by the RnBXclusive.com website was illegally obtained from artists, leading the industry to attribute losses of approximately £15m per year to the site's activity.
"Members of the public can become facilitators of organised crime by obtaining property or services from its perpetrators. Soca is committed to raising awareness of this threat, its potential consequences, and the steps people can take to avoid involvement."