Doctors sound the alarm about increased number of sex infections

The Health Protection Agency revealed diagnoses of sex infections rose by 3% to 790,387 from 2004 to 2005.

The biggest rise was seen in syphilis cases, which rocketed by 23% to 2,807, but Chlamydia, genital warts and herpes also registered increases.

New cases of gonorrhoea bucked the trend by falling by 13% - a substantial drop for the second successive year, BBC News reports.

The highest rates of infection for both sexes were among 16 to 24-year-olds,according to Guardian Unlimited.

The 2005 figures show the government's national strategy for sexual health is failing to deliver. Published in 2001, the 10-year programme committed extra investment worth £47.5m to reduce STI transmissions, which soared during the 90s.

Professor Peter Borriello, director of the HPA's centre for infections, welcomed the "significant" fall in gonorrhoea cases last year but warned that "much has to be done" to tackle the "disappointing" rates of infection overall.

The chief executive of the Family Planning Association, Anne Weyman, said better public awareness screening services introduced as part of the government's sexual health strategy meant more people were coming forward for testing and treatment.