In 2006, over 370,000 new sexually transmitted infections were diagnosed - up 2.2 percent on 2005, the HPA said Friday.
In general, sexual infections - including chlamydia, herpes and warts viruses - have been almost continually rising since the 1990s, it said.
Young adults are disproportionately affected by sexually transmitted infections, accounting for 65 percent of all chlamydia, 55 percent of all genital warts and 48 percent of gonorrhea diagnoses across the UK in 2006.
An estimated 73,000 adults are now living with HIV in the UK while a third of them don't know they have the virus.
HIV transmission seems to be a particular problem among gay men - the HPA estimates just over 2,700 new HIV infections among them in 2006.
Professor Pete Borriello, director of the HPA Center for Infections, recommends that gay men should have regular HIV tests; HIV tests should be standard in clinics for sexually transmitted diseases; and young sexually active adults should be screened for chlamydia annually and after a partner change.
