The rate of suicides in Britain has risen sharply to its highest level since 2002, with men accounting for three-quarters of the number of people who took their own lives last year, official figures show.

A total of 6,507 suicides were registered by coroners in the UK – 11.2 per 100,000 people – in 2018, up 11.8% on the previous year, according to the Office for National Statistics.

Particular concerns were raised over an increase in the rates of young people aged from 10 to 24 killing themselves, with the overall rate for that age group reaching a 19-year high and the rate for young females reaching an all-time high.

Ruth Sutherland, the chief executive of Samaritans, said: “It is extremely worrying that, for the first time in five years, the suicide rate in the UK has increased, with 686 more deaths than in 2017.

“Every single one of these deaths is a tragedy that devastates families, friends and communities. Whilst the overall rise has only been seen this year – and we hope it is not the start of a longer-term trend – it’s crucial to have a better understanding of why there has been such an increase.

“We know that suicide is not inevitable; it is preventable, and encouraging steps have been made to prevent suicide, but we need to look at suicide as a serious public health issue.”

According to statisticians, the rise in suicides in 2018 was largely driven by an increase among men, who took their own lives at a rate of 17.2 per 100,000, compared with 15.5 in 2017.

The overall increase was statistically significant and reversed a trend of continuous decline since 2013, according to Nick Stripe, the head of health analysis and life events at the ONS.

People aged 45 to 59 had the highest rates of suicide, at 27.1 per 100,000 for men and 9.2 per 100,000 for women. Stripe also pointed to big increases in the rate of suicide among young people. In 2018, 730 people aged 10 to 24 killed themselves, the highest number since 2000, when 749 took their own lives.

The rate among 20- to 24-year-old males leaped 31% to 16.9 per 100,000, from 12.9 a year earlier. Among females aged 10 to 24, despite a low number of suicides overall, the rate rose to its highest level, 3.3 per 100,000.

Scotland had the highest suicide rate in Britain, with 16.1 deaths per 100,000 people (784 deaths), followed by Wales with 12.8 per 100,000 (349 deaths) and England the lowest with 10.3 deaths per 100,000 (5,021 deaths). The rates for Northern Ireland will be published later this year.

Outside Scotland, the area with the highest suicide rate for men was the north-east, with 20.4 per 100,000 taking their own lives; for women it was Wales that had the highest rate, at 6.9 per 100,000. London and the south-east had the lowest rates for both sexes.

The ONS said the exact reasons for the rise were unknown but that changes made in the last year to the way coroners record such deaths may be a factor.

In July 2018, the standard of proof used by coroners to determine whether a death was suicide was lowered from beyond reasonable doubt – the same standard as a criminal trial – to the balance of probabilities.

Stripe said: “Looking at the overall trend since the early 80s, we are still witnessing a gradual decline in the rate of suicide for the population as a whole. We will continue to monitor the recent increase, to help inform decision makers and others that are working to protect vulnerable people at risk.”

• In the UK and Ireland, Samaritans can be contacted on 116 123 or email jo@samaritans.org or jo@samaritans.ie. 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 helplines can be found atwww.befrienders.org.