Internet service providers are being urged by the government to provide access to pornographic websites on an "opt-in" basis.
The move is designed to protect children from accessing pornography.
"This is a very serious matter. I think it is very important that it's the ISPs that come up with solutions to protect children," communications minister Ed Vaizey told the Sunday Times.
"I'm hoping they will get their acts together so that we don't have to legislate, but we are keeping an eye on the situation and we will have a new communications bill in the next couple of years," he said.
Vaizey is to discuss the plans with internet providers, such BT, Virgin Media and TalkTalk.
Jim Killock, executive director of the digital civil liberties organisation the Open Rights Group, said attempts to censor pornographic sites were misguided.
"This is the wrong way to go. If the government controlled a web blacklist, you can bet that Wikileaks would be on it. This is not about pornography, it is about generalised censorship through the back door," he said.