More than 2,000 out of every 100,000 young people were diagnosed with the sexually transmitted infection (STI) chlamydia last year, latest figures show.

The disease can leave sufferers infertile if it is untreated and although symptoms can include pain urinating or unusual discharge from the penis or vagina, sufferers are often symptom-free and don’t know they have the infection.

There were 2,331 cases per 100,000 people aged 15 to 24 in Barking and Dagenham in 2012, according to statistics released by the Department of Health agency, Public Health England (PHE).

This is the 10th highest rate out of all 33 London boroughs.

The rate of those diagnosed with the same disease aged 25 and over was just 168 per 100,000.

Overall, 1,062 STIs per 100,000 people were found in 2012, the 20th highest in the capital.

The rate for gonorrhoea was 65 per 100,000 people, while herpes was 74, syphilis was three, and genital warts was 12.

London has the highest rate of STIs of any region in England, with 111,451 cases last year.

Dr Paul Crook, an STI epidemiologist for PHE London, said too many people in the capital, especially the young, were putting themselves at risk by having unsafe sex.

He added: “Some STIs, such as chlamydia, may not cause any symptoms and if this goes undiagnosed and untreated, it can lead to fertility problems later on in life.

“That is why we recommend that people who are under 25 years old and sexually active come forward for screening for chlamydia every year, and thousands of people do take this advice.”

He said that the rise in numbers of people being diagnosed can partly be put down to STI screening improvements.