A Birmingham University study indicates that an illegal file-sharer downloading popular content would be logged by a monitoring firm within three hours. The team said it was "surprised" by the scale of the monitoring.
Copyright holders could use the data to crack down on illegal downloads.
The three-year research was carried out by a team of computer scientists who developed software that acted like a BitTorrent file-sharing client and logged all the connections made to it.
BitTorrent is a method of obtaining files by downloading from many users at the same time.
The logs revealed that monitoring did not distinguish between hardcore illegal downloaders and those new to it.
"You don't have to be a mass downloader. Someone who downloads a single movie will be logged as well," said Dr Tom Chothia, who led the research. "If the content was in the top 100 it was monitored within hours," he said. "Someone will notice and it will be recorded." Less popular content was also monitored although less frequently, the study indicated.
Source: BBC News
