About three hours after joining a file-sharing BitTorrent swarm you are likely to come up on the radar of copyright enforcement agencies, a new study reveals. Most of them are not reporting publicly that they engage in such monitoring.

­The higher a torrent file is on most popular list, the faster the monitors are responding, Researchers from Birmingham University reported at the SecureComm conference in Padua, Italy, this week.

They also found that independent blocklists, which torrent users manually create to ward off suspected monitor organizations, failed to include many of the peers the researchers identified as suspicious.