Around 13,000 BT customers have been identified and accused of illegally downloading content and will be notified via legal letters in the New Year.
The letters come from law firm ACS:Law and will demand payments of hundreds of pounds. Other ISP customers are also to be targeted under the law firm's investigations.
Since 2007, ACS:Law has sent an estimated 25,000 such letters to people it believes to have used peer-to-peer sites to share copyrighted material. The law firm’s activity has been monitored by consumer rights group Being Threatened.
The law firm obtains its information on individuals who have been file sharing through data monitoring companies that track file-sharing networks.
An ACS:Law spokesperson said that the targeting of BT customers was the result of information received from German tracking service DigiProtect, which is believed to have identified 25,000 IP addresses linked to illegal downloading.
BT has told media that could take up to nine months to supply ACS:Law with the details, which would see the letters sent next August.
The piracy alert comes as business secretary Peter Mandelson's three-strikes proposal for unauthorized file downloads is being heavily debated. The proposals mimic France’s recent laws, which allow ISPs to cut off internet services to customers after multiple warning letters.
The harsh approach is unlikely to receive the support of the EU, which passed its telecom reform package last week and intimated that customer rights should be highlighted in piracy allegations.
Last week Virgin Media announced that will trial software to measure the extent of illegal file-sharing among its customers, as part of its music subscription service with Universal. Virgin will be the first company to use new technology from UK firm Detica, which claims to anonymously track copyright infringement.
Meanwhile, a pub owner in the UK has been fined £8,000 ($13,500) because a customer unlawfully downloaded copyrighted material over its open Wi-Fi hotspot, according to the managing director of hotspot provider The Cloud. The law surrounding liability for open Wi-Fi networks usage remains a gray area.