Children aged five and under are at risk of becoming addicted to the internet in a trend that could damage their mental health, according to Barnardo’s.

The charity said very young children – one as young as two – were learning to access websites, for example YouTube and those related to children’s television programmes, as a result of their parents giving them access to smartphones or tablet computers to distract or entertain them.

Barnardo’s is concerned that early access to electronic devices could lead to both addiction and a loss of key social skills as families spend less time talking among themselves.

It warns in a report into the effects of technology and social media on children that platforms such as Snapchat, Instagram and Twitter are having a “disturbing” impact on the mental health of under-18s.

The report said: “Barnardo’s practitioners raised concerns in relation to the social and emotional development of very young children when they interact with social media.

“Worries regarding addiction and the substitution of time spent with family for the use of social media were issues that were felt to cause problems related to mental health and emotional wellbeing in this age group.

“Key apprehensions included the failure to think creatively, interact with others socially and manage their own emotions.”

The report’s findings were based on testimony from 80 support workers who work with under-18s at 30 Barnardo’s projects across the UK. Many of their clients are young people who are particularly vulnerable because they are or have been in care, in a gang, or under the supervision of a pupil referral unit.

The research also found that:

• A third of five-to-10-year-olds have been the victims of cyberbullying.

• Children of that age are being exposed to unsuitable or harmful material online.

• 79% of support workers have dealt with 11-to-15-year-olds who have suffered cyberbullying.

• 58% of those helping those 16 or over had seen cases of self-harm and attempted suicide linked to the young person’s history of cyberbullying.

• 78% of support workers had come across young people of that age who had been groomed online.

“Although the internet offers incredible opportunities to learn and play, it also carries serious new risks from cyberbullying to online grooming,” said Javed Khan, Barnardo’s chief executive. “These risks can have a devastating impact on the lives of the UK’s most vulnerable children.”

However, the charity added that social media can also offer benefits, such as reducing vulnerable young people’s isolation and loneliness, and letting them link up with people like them.

“These findings shine more light on the potentially harmful relationship between social media and youngsters’ mental health and wellbeing, with this report suggesting it could be a problem for some children, from a very young age,” said Claire Murdoch, NHS England’s national mental health director.

Social media platforms need to start paying a levy to help fund NHS treatment of the growing number of children and young people whose mental health is harmed by using them, Murdoch added.

Barnardo’s highlighted the case of an 11-year-old girl who tried to end her life after suffering cyberbullying by young people who found out that her father had been sent to prison and was on the sex offender register.

“I got horrible messages from children saying: ‘Your dad’s a pervert, you might as well kill yourself now.’ Due to the comments, I began to hate myself and felt ‘outside’ of everything, so then I tried to kill myself,” the girl told the charity.

Tom Madders, campaigns director at the charity Young Minds, said: “Using phones and being online from a young age, including having access to social media accounts, has become a normal part of life for many children. The children and young people we work with tell us about the positives of using technology, but also that being exposed to harmful content or being bullied round the clock on social media can have a serious impact on their mental health.”

In a white paper in April on combating online harm, the government pledged to take action to tackle the problem. That included putting a new legal duty of care on providers to ensure that young users do not come to harm from accessing their content.