The government’s communications minister Ed Vaizey recently proposed that ISPs block porn and that all users be automatically opted-out.
But the proposal has raised serious censorship issues.
In an online debate hosted by the Daily Telegraph, both companies expressed concern over Vaizey’s proposal noting that the plans hadn’t been thought through.
They cited defining the boundaries of adult content, responsibility for censorship and a host of practical and legal concerns as thorny issues.
Duncan Higgins, Virgin Media’s head of broadband media said that parents need to control what their children view on the web.
"There needs to be a real drive to getting parents to understand the issue," he said.
A Virgin spokesperson added, "We're absolutely committed to [Mr Vaizey's] aim of greater protection of children online."
Tim O'Sullivan, BT's public affairs director echoed Virgin’s stance and said, “BT offers parental controls and we believe such controls and education are the best way to approach the issue.”
Britain’s two major ISPs will reportedly issue new printed and online parental control guides in March.
BT broadband users will also have the opportunity to install the company's free Family Protection software.