The bullying of young people online and in text messages has grown significantly worse in recent years, according to the UK’s media watchdog.

An Ofcom report published on Tuesday found that the proportion of 12- to 15-year-olds who said they had been bullied over text messages and apps increased from only 2% in 2016 to 9% last year, while the proportion of those who reported having been bullied on social media nearly doubled from 6% to 11% in the same period.

The research suggested many young people felt the need to use multiple social media profiles set to be visible to different groups of people to project different images to each social group.

“Children posted different content on these profiles depending on who they allowed to see each profile; more visible accounts tended to be more highly curated, showing a ‘picture-perfect’ self, while less visible accounts tended to be used to show their ‘real self’ to more carefully controlled circles of close friends,” the report said. “In this way, while some may feel pressure to look attractive or popular on social media, children are finding strategies to still be themselves, at least some of the time.”

Ofcom said children were experiencing increasing levels of bullying through services such as WhatsApp and were exposed to more “nasty” material online.

While the proportions are relatively low, the news of the sharp increase coincides with a debate over the role of social media firms in protecting young people online. On Monday, Facebook’s new head of global affairs, the former deputy prime minister Nick Clegg, told the BBC the company would do “whatever it takes” to do so.

He was responding to questions about the case of 14-year-old Molly Russell, who took her own life in 2017. After her death, her account on Instagram – owned by Facebook – was found to contain material about depression and suicide.

That led the health secretary, Matthew Hancock, to warn Facebook and other social firms that he would seek ways to use the law to force them to act over such content, should they refuse to take sufficient action voluntarily.

In the UK, Samaritans can be contacted on 116 123 or email jo@samaritans.org. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In Australia, the crisis support service Lifeline is 13 11 14. Other international suicide helplines can be found at www.befrienders.org.