UK arts lobby groups have demanded BT block access to the BitTorrent file sharing website, The Pirate Bay.
Music industry trade body, the BPI, said it would take legal action if the telecoms firm refused to co-operate.
The movie industry has already forced BT to block Newzbin 2, a members-only which aggregates illegally copied material.
BT said: "We can confirm we are now in receipt of a letter from the BPI. BT is considering its response."
The telecoms operator added that a court order would be needed before any blocking could begin.
A source told the BBC the firm was unlikely to fight a lengthy legal battle as it had in the Newzbin case.
"We would not tolerate Counterfeits 'R' Us on the High Street - if we want economic growth, we cannot accept illegal rip-off sites on the internet either," said the BPI's chief executive, Geoff Taylor.
http://www.bbc.co.uk/news/technology-15598438
Unfortunatly blocking sites does not work
Newzbin claims BT block 'not working'
BT has started blocking access to the controversial website Newzbin 2.
But the group behind the site claims that its users are still able to access it via a workaround that it issued in September.
Newzbin 2 is a members-only site which aggregates a large amount of the illegally copied material found on Usenet discussion forums.
Last month the movie industry won the right to impose blocks via BT.
BT told the BBC that the block had come into force on 2 November.
It is implementing the blocks by tweaking software developed to prevent users from finding websites showing images of child abuse.
"Newzbin have offered their customers a client for over a month that they claim will bypass Cleanfeed. However we're not in a position to comment on whether that claim is true or not," said a spokesman.
The group behind Newzbin 2 commented: "We've heard that the British Telecom censorship of the free web has begun."
It told the BBC that 93.5% of its active UK users have downloaded the workaround software.
It is not willing to reveal how the code attempts to get around the Cleanfeed block.
However, tests run by website TorrentFreak found that the program relies on encryption to hide communication between users and Newzbin2.
Another technique it uses is to route all traffic through a well-established system known as TOR, which masks the identity of users and what they are trying to look at.
http://www.bbc.co.uk/news/technology-15572495