By Emma Henry and PA
Last Updated: 1:48pm GMT 22/11/2006
An estimated 63,500 adults are now living with HIV in the UK - with around a third unaware of their infection, according to a report released today.
The Health Protection Agency's report said that around 20,100 people did not know they were infected.
The report, entitled A Complex Picture, is being launched ahead of World Aids Day on Dec 1 and contains "the most up-to-date description of both HIV and aids and sexually transmitted infections in the UK".
According to the United Nations, an estimated 39.5 million people are now living with the aids virus worldwide as infection rates and deaths continue to mount.
Dr Valerie Delpech, an HIV expert at the Health Protection Agency, said: "We are seeing an ever increasing pool of people living with HIV and aids in the UK.
"This is due to people living longer with HIV due to advances in treatment, sustained levels of newly acquired infections in gay men, further diagnoses among heterosexuals who acquired their infection in Africa and cases being picked up earlier."
She said that the high level of new HIV cases being diagnosed continued in 2005 with 7,450 cases recorded, including almost 2,400 new cases in gay men.
Three in every one hundred gay men who attended an STI clinic last year acquired their HIV infection during 2005, most probably within the UK.
Dr Delpech continued: "The global HIV epidemic continues to affect black and ethnic minority populations in the UK and where ethnicity was reported, this group accounted for two-thirds of all new cases reported in 2005 (3,691 out of 5,902).
"Although the majority of these are contracted in countries of higher prevalence and particularly through links with Africa, more of these cases are now being contracted within the UK.
"The number of reports of HIV infected black Africans who contracted their infection in the UK increased from 43 in 2000 to 182 in 2005."
She said that despite some improvement there was concern that many HIV infections are still being diagnosed late, reducing life expectancy as treatment is not begun when needed.