Virgin Media and TalkTalk have been approached by the Motion Picture Association (MPA) to establish whether they would agree to block copyright-infringing web site Newzbin2.
BT was informed by the High Court last month that it had 14 days to block the web site following a ruling that has now set a precedent for future blocking.
Newzbin2 offers users access to copies of films and television programmes without permission from the copyright holders.
Both Virgin Media and TalkTalk have now received letters from MPA asking the ISPs whether or not they would object to a court order to block access to Newzbin2.
TalkTalk has said that it is "considering its position" and that there are "some objectionable elements to the proposed injunction".
"We will only block access to a website if ordered to do so by court," said a TalkTalk spokesperson.
Virgin Media has taken a similar line, but has also commented that court orders to block sites must be accompanied by new models to support creative industries in a digital age.
"The recent Newzbin2 ruling clarifies the legal process for content owners to challenge alleged copyright infringement," said a Virgin Media spokesperson.
"As a responsible ISP, we comply with any court order addressed to us, but strongly believe such deterrents need to be accompanied by compelling legal alternatives, such as our agreement with Spotify, which give consumers access to content at the right price."
MPA, with support from the creative industries, last month won a blocking order from the High Court in the face of stiff resistance from BT, which ended up having to pay the lion's share of the costs of the application.
"BT did not consent to the order or even adopt a neutral stance on the application," said Justice Arnold of the High Court.
"On the contrary, BT's stance was one of all-out opposition. To that end, it served evidence in opposition, instructed two leading counsel and resisted the application on eight different grounds," added Justice Arnold.
"Each of these grounds failed. In my view the costs of the application from 17 December 2010 to 28 July 2011 should be borne by BT."