David Cameron’s measures to limit online pornography have come under attack – from the European Union. Despite its reputation for regulation and authoritarian measures, Brussels is currently considering proposals to make it illegal for mobile and internet firms to automatically block material.

According to the Sunday Times, a leaked policy proposal document shows that the Council of the European Union is considering measures which will stipulate that so-called parental control measures would only be allowed where the end user has opted in and has the ability “to withdraw this consent at any time”.

If passed, the regulation would render illegal British government rules stipulating that mobile phone networks and public Wi-Fi providers put in place automatic blocks on any material not deemed to be child friendly. Sky broadband customers also have to navigate past an automatic block by actively opting in to accessing adult material.

John Carr, a government adviser on internet safety, said: “The risk is that a major plank of the UK’s approach to online child protection will be destroyed at a stroke. The prime minister and chidren’s organisations have been campaigning for it, and the industry have been willing to do it. It seems incredible that an obscure measure from Brussels could bring this to a halt”.

Hamish MacLeod, chairman of the Mobile Broadband Group, said that the filters had been an industry standard for a decade, adding: “This will undermine the government’s family-friendly policy for the internet. Anybody can buy a prepay phone, so are we seriously saying that children will be given the responsibility to ask for parental controls?”

Mr Cameron introduced plans for all internet providers to automatically block pornography in 2013, claiming that it would help parents prevent their children accessing porn. He told the BBC: “All I am saying is that as a parent and as a politician I think other parents would welcome the fact that when you sign up to an online account you get a prompt to think about whether you want an internet in your house where your children can sometimes accidentally or on purpose search for pornographic images.

“We are giving parents, I think, the opportunity to take a more positive role. We are not telling parents what to do we are helping them with something they have asked us in many way to do.

“It’s certainly not lecturing people about what they should or shouldn’t do – it is helping them with something that people continually tell me they’d like some help with.”

But one of his ministers, Nick Boles, suggested the government should take a more libertarian stance, stating “As a Conservative, my starting point is that people should be free to live their lives as they choose. I am not going to start lecturing consenting adults about their  private enjoyment of legal pornography.”

A spokesman for the culture department, led by John Whittingdale, said: “The UK government will not support any proposals that do not allow us to maintain our child protection policies or bring forward new similar policies. The UK has played a leading role in shaping the EU proposals on net neutrality and made sure that the current draft text allows Internet Service Providers to continue to implement family-friendly internet filters.”

The EU’s measure will not affect laws on accessing criminal material.