The number of under-16s contracting sex infections has rocketed in five years, new government figures show today.

The number of diagnoses of sexually transmissed diseases among young people in England rose by 58% from 2,474 in 2003 to 3,913 in 2007.

The biggest increase was in cases of chlamydia, the most common sexually transmitted infection, which rose by 90%, with genital herpes up by 42% and genital warts by a third. Cases of syphilis doubled from three to six, but peaked in 2005 at 17.

The figures from genitourinary medicine clinics and the national chlamydia screening programme were released in a Commons written answer to the Liberal Democrat health spokesman, Norman Lamb.

The national chlamydia screening programme has been phased in since April 2003 with testing in community contraceptive clinics, some further education colleges, and more recently through postal testing kits and pharmacies.

A Department of Health spokesman said: "The programme has helped us to screen an increasing number of people for chlamydia. Since 2008, all primary care trusts have been reporting to the programme, which accounts for the recent increase in reported cases."

Lamb said: "This shocking increase is a damning indictment of the government's complacency when it comes to the sexual health of our children.

"The number of youngsters contacting STIs is very disturbing. Children must be informed about the risks involved in sexual relationships and taught how to be safe.

"The government has slashed public health spending over recent years. This short-sightedness is putting a whole generation at risk of a sexual health crisis."