Social media use has contributed to the rise in self-harm among teenage girls, the health secretary, Matt Hancock, has said, accusing big tech firms of doing nothing to enforce minimum age rules.

Hancock, a keen user of social media who created his own app for constituents, has repeatedly warned of the dangers posed to teenagers by the influence of some sites and has said he does not let his own young children use them.

His department is set to produce the first official guidelines on the maximum amount of time young people should spend on social media, as well as probing the links between excessive use of social media and child mental health problems.

The health secretary said he believed social media “has got a part to play” in rising mental health problems for children and young people.

“If you look at the figures, there’s an increase in self-harm amongst teenage girls but not amongst teenage boys,” he told the House magazine. “And that implies that something happened in the last decade to increase the pressure on teenage girls.

“Now, thankfully that hasn’t yet been reflected in a material change in suicide rates, which is the ultimate failure of somebody’s mental health – suicide rates are currently at a seven-year low. But that implies that there is a problem in terms of the pressures being put on teenage girls and the consequences for their mental health.”

Hancock suggested he was not convinced by some suggestions that social media companies should pay a levy to help fund children’s mental health services. “Whether you link the two directly or not is less important than whether we get the funding into children’s mental health services,” he said.

However, he said there “absolutely should” be a minimum and enforced legal age requirement to use social media sites.

“The terms and conditions of the main social media sites are that you shouldn’t use it under the age of 13, but the companies do absolutely nothing to enforce against that. And they should, I think that should be a requirement,” he said.

“You shouldn’t be on WhatsApp, according to their own terms and conditions, before you’re 16. And yet, the pressures that people feel under when they’re on a WhatsApp group to respond, to wake up in the middle of the night to get back to messages – this is teenagers or young kids who aren’t even teenagers yet.

“So, if the company says that you shouldn’t be on it till 16, they should do something about that and they should empower parents to allow it to happen.”