Sexually transmitted infections hit a new record last year. The total increased by 6 per cent in 2007 to 397,990 new cases.

Half involved young people aged 16 to 24, who comprise just 12 per cent of the population. The rise in infections – 72 per cent in a decade – was attacked by the Tories who accused the Government of "shameful complacency" about the problem.

But MPs and sexual health charities agreed that the best approach was to improve screening, diagnosis and treatment rather than attempting to curb sexual activity.

Professor Peter Borriello, the director of the Centre for Infections at the Health Protection Agency (HPA), said: "For young people a casual shag is... part of life. Increasingly a shag now stands for Syphilis, Herpes, Anal warts and Gonorrhoea... which means wear a condom."