File photo: A total of 45 other countries had lower proportions of unhappy girls, including poorer nations such as Bulgaria, Thailand, Poland and Mexico.

British teenage girls are among the most miserable in the world due to pressures such as social media, reveals a major international study.

The country came fourth in a table of nations ranking dissatisfaction with one in five girls saying they are not happy with their lives.

A total of 45 other countries had lower proportions of unhappy girls, including poorer nations such as Bulgaria, Thailand, Poland and Mexico.

The research by the Organisation for Economic Co-operation and Development came from surveys of 540 000 children aged 15 in dozens of countries worldwide.

It also found a high proportion of girls in the UK skipped breakfast or dinner, key indicators of eating disorders.

Experts said the results were "worrisome" and called on policymakers to wake up to the "pressure we are putting on girls". They warned that cyberbullying and peer pressure from social media were making British girls feel "less happy with themselves" despite their wealth in comparison to those in other countries.

Youngsters in the country spent 188 minutes per weekday on average browsing the web outside school. Only those in Chile and Brazil spend longer online. The OECD found that those who were online a lot had a weaker sense of belonging, felt lonely and were more likely to be bullied.

Chief of staff Gabriela Ramos said: "We confirm that girls are subject to a lot of pressures from social media, that they are less happy with themselves.

"We need to recognise that there is an issue with the pressure that we are putting on girls."

Asked why girls are more affected in this country, she said: "Probably because they spend more time on the internet. That’s one of the issues that we have. The UK is top of the class in terms of usage of internet. It’s very high."

She added girls in the UK were suffering more than boys from online bullying by their peers.

"Girls in the UK are [affected] the worst," she said. "They are in a higher percentage reporting mental health problems and being subjected to bullying or nasty rumours."

The report notes other research has shown "exposure to images of overly thin girls and young women in traditional media and to photo-sharing in social media has a significant negative impact on girls."

The study found that 19.4 percent of girls in the UK reported feeling "not satisfied" with their lives compared with 11.9 percent of boys. The average proportion of dissatisfied girls across all OECD countries was 14.3 percent.

Britain came fourth out of 49 when countries were ranked according to those with the highest proportions of girls feeling unsatisfied. Only Korea, Turkey and Tunisia had higher figures. When girls in the UK were asked to rate their life satisfaction from zero to ten, the average answer was 6.6 compared with 7.3 for boys.

Only Turkey, Korea, Italy, Greece, Taipei, Macao and Hong Kong had a lower average score for girls. The UK’s average ranking for both genders was the 11th lowest across 48 countries, with those faring better including Mexico, Brazil and Bulgaria.

An NSPCC spokesperson said: "The report highlights the huge bullying problem we have in the UK, with almost one in four 15-year-olds having to endure this. For over 30 years it has been among the top problems young people have contacted Childline about.

"Worryingly, an increasing amount of this behaviour is now taking place online with many victims left feeling like there is no escape from their tormentors."