Ofcom has launched investigations into two pornographic sites it believes may be falling foul of the UK’s newly introduced child safety rules.

The regulator said two companies – including one running a so-called “nudifying” service – had failed to detail how they were preventing children from accessing their platforms.

Ofcom announced in January that, in order to comply with the Online Safety Act, all websites on which pornographic material could be found had to introduce “robust” age-checking techniques by July.

It said the two services it was investigating did not appear to have any effective means of checking the age of users.

Firms found to be in breach of the Act face huge fines.

The regulator said on Friday that many services had, as required, provided details of “highly effective age assurance methods” they were planning to implement.

They added that this “reassuringly” included some of the largest services that fall under the rules.

It said a small number of services had also blocked UK users entirely to prevent children accessing them, it said.

The two companies it is investigating did not respond to its request for information or show they had plans to introduce age checks.

The “nudifying” technology one of them features involves the use of artificial intelligence (AI) to create the impression of having removed a person’s clothing in an image or video.

The Children’s Commissioner recently called on the government to introduce a total ban on such AI apps that could be used to create sexually explicit images of children.

All websites where a user might encounter pornographic material are required to demonstrate the robustness of the measures they are taking to verify the age of users.

These could include requiring UK users to provide photo ID or running credit card checks.

These could even apply to some social media platforms, Ofcom told the BBC in January.

The rules are expected to change the way many UK adults will use or encounter some digital services, such as porn sites.

“As age checks start to roll out in the coming months, adults will start to notice a difference in how they access certain online services,” said Dame Melanie Dawes, Ofcom’s chief executive, in January.

In April, Discord said it would start testing face-scanning as a way to verify some users’ ages in the UK and Australia.

Experts said it marked “the start of a bigger shift” for platforms as lawmakers worldwide look to impose strict internet safety rules.

Critics suggest such measures risk pushing young people to “darker corners” of the internet where there are smaller, less regulated sites hosting more violent or explicit material.