The British Board of Film Classification will be responsible for regulating age checks for UK users of online porn websites, if the government gets its way.

The UK's Ministry of Fun* has proposed the BBFC as the regulator for ensuring sites are using age-verification controls.

These checks were made mandatory by the Digital Economy Act, and will require residents wishing to access porn sites to prove they are 18 or over.

The government said the BBFC had "unparalleled expertise" in classifying content and a "proven track record of interpreting and implementing legislation" as the authority responsible for video age ratings.

But campaigners have questioned the choice, saying that it hands over too much control to the BBFC, making it a de facto censor of online porn websites – as it can block sites that don't comply by telling UK ISPs to restrict access to them.

"While BBFC say they will only block a few large sites that don't use age verification, there are tens of thousands of porn sites," said Jim Killock, director of the Open Rights Group.

"Once MPs work out that age verification is failing to make porn inaccessible, some will demand that more and more sites are blocked. BBFC will be pushed to block ever larger numbers of websites."

Killock was also sceptical of the BBFC's ability to ensure age verification is safe, secure and anonymous, saying it is "powerless to ensure people's privacy" and the development of age-verification products is "out of BBFC's hands".

There are particular concerns over how data collected from viewers will be used. Information Commissioner Elizabeth Denham previously warned that information like passport details could be "vulnerable to misuse and/or attractive to disreputable third parties".

The new law, experts say, could also encourage users to be less security conscious, leaving them susceptible to dodgy actors setting up fake sites. As security researcher Alec Muffet said on the issue:

Fake porn sites (especially outside the UK) abound; with this mechanism you are training people to give their phone numbers to untrusted websites (whilst still "rewarding" them with porn) and the websites can sell/give these numbers onward to marketing companies.

In addition, there are concerns about the impact the law will have on the porn industry, which is already dominated by MindGeek, the owner of mainstream porn sites like PornHub and RedTube, and video producers such as Brazzers.

That means its product, AgeID – effectively an aggregator of verification solutions with a federated login – is likely to dominate the market.

Critics, such as independent pornographer Pandora/Blake, argue this will allow MindGeek to expand its monopoly, if it licenses AgeID to other porn sites.

On their blog, Pandora/Blake said the end result was "regulatory capture", as "smaller sites like mine will effectively have to pay a 'MindGeek tax' to our biggest competitor".

Security concerns are not helped by MindGeek companies' poor security history. PornHub users suffered a malvertising campaign this year and in 2012 a YouPorn data breach spilled 1 million users' details. ®

*The Department for Digital, Culture, Media & Sport – aka the fun stuff...