The government is considering plans to force UK-based adult websites to verify users are over the age of 18, and block access to those that cannot prove their age.

The plans would add a second level of government control over adult websites, with ISPs already presenting their users with the option of “family-friendly” filters, described by many as the Great Firewall of Britain for its similarities with the censorship of the internet in China.

Campaigners have long called for age verification systems on adult websites, but the major problem facing authorities is that while they can force UK websites to comply, websites from other countries, including the US where most internet pornography is produced and published, would be exempt. Any such law would prevent UK-based adult websites competing on the internet, as users from the UK and abroad would move to other websites to avoid the hassle and possible embarrassment of proving their age or identity to access pornography.

Legislation to impose a system of age verification is being drawn up by the department for culture media and sport (DCMS), and the Sunday Times claims it will include the introduction of technologies similar to those used by betting websites with credit card and bank information used to verify users’ identities. However, unlike betting websites, the most popular adult websites are free to access and users do not currently expect to have to provide personal details to access free content online.