Virgin Media, Sky and TalkTalk have been asked to block access to Newzbin2, a members-only group which provides links to pirated films and music.
BT has already barred its customers from accessing the site, following a court case brought by the Motion Picture Association.
The MPA is now extending its net in a UK-wide crackdown on piracy.
TalkTalk said it was "considering its response". Sky and Virgin Media signalled they would obey court orders.
Legal battle
"There are some elements of the order, for instance that we have to pay the costs of implementing it, that we think are inappropriate," Andrew Heaney, head of regulatory affairs at TalkTalk, told the BBC.
BT has estimated that the block against Newzbin cost it around £5,000 to set up.
"In a sense it wouldn't be worth having a legal battle over that but if the costs get a lot more we may reserve the right to contest it in the future," Mr Heaney said.
The MPA confirmed that it had written to the major ISPs.
"We are involved in constructive discussions but we are not going to comment in detail at this stage," said an MPA spokesman.
Virgin Media acknowledged that it had also received a letter as a preliminary step towards a formal court order.
"The recent Newzbin2 ruling clarifies the legal process for content owners to challenge alleged copyright infringement," said a Virgin Media spokesman.
"As a responsible ISP, we will comply with any court order addressed to us but strongly believe such deterrents need to be accompanied by compelling legal alternatives."
Sky also indicated that it was likely to comply with any court order.
"When presented with undisputed and legally robust evidence of copyright breaches, we will take appropriate action in respect to site blocking," said a spokesman.
Workaround
The MPA has hailed the Newzbin block as a victory in its ongoing fight against piracy which it estimates costs the industry billions of pounds each year.
It has vowed to implement similar blocks against other sites offering links to pirated movies.
Newzbin said on the day that BT's block began that it was "unaffected" because it had issued a software workaround. It claimed the code was being used by over 90% of its members.
In response, the MPA said that despite ways to get around the block, it was hopeful that the move would deter the "vast majority of customers".
Web blocking appears to be the new weapon of choice for the creative industries. On 4 November BT received a letter from the BPI, the UK's music industry trade body, asking it to block access to BitTorrent file-sharing website The Pirate Bay.
