David Cameron has announced plans to help protect children from adult content online, by insisting all new computers ask whether there are children in the household when they are turned on for the first time.

The prime minister described the plans in an article for the Daily Mail as "radical" and insisted that they will help parents protect children from internet pornography, violence and other unsuitable websites, adding that such content is "a silent attack on innocence" and that childhood should be "untainted by the worries and complexities of adulthood."

If the plan is backed by manufacturers, it would mean that owners of every brand new computer would be asked if there are children in the household when they are first turned on. If the user answers positively, they will be prompted to adjust their internet filters accordingly.

If parents repeatedly click OK to get through the process more quickly, the computer would automatically block access by any user to sites containing pornography and self-harm. Internet service providers (ISPs) would also be required to verify the age of the person setting the controls, so that a child can't do it.

The technology will also show parents how to limit access to social networks like Facebook and Twitter after a time of their choice, so children can't view social media on their own at night, and block access to certain websites altogether.

The PM announced that Conservative MP Claire Perry will be appointed as his advisor on reversing the commercialisation and sexulisation of children, and she will be in charge of implementing the new web filters; Perry has also led a campaign for broader, automatic blocking of adult content online.

Critics

Despite claims from critics that MPs were putting ISP's profits ahead of protecting what children see online by vetoing an opt-in system for users to view all adult content with one click, Cameron insisted it is clear that a "more sophisticated system" will be more effective, arguing that on/off filters are not used because they are so wide-ranging that parents turn them off through frustration.

"The point is we need a more sophisticated system than this," Cameron said. "One that allows parents to tailor exactly what their children can see. This is what child safety experts recommend."

The PM added: "With our new system, every parent will be prompted to protect their child online. If they don't make choices, protection will be automatically on. No other government has taken such radical steps before.

"And once all this is in place, Britain will have the most robust internet child protection measures of any country in the world - bar none."

In his Daily Mail article the Conservative leader went on: "All this comes back to something really important. It's not just about the internet, or modern technology - it's about childhood.

"These should be distinct and precious years, full of security and love, untainted by the worries and complexities of adulthood. From one parent to another, I pledge to do whatever I can to preserve that innocence and protect our children. Nothing matters more."