New figures show a slight decline in the number of gay and bisexual men being diagnosed with HIV but campaigners estimate that one in four with the disease are unaware they have it.

The figures for 2009 HIV diagnoses were released by the Health Protection Agency today and show that men who have sex with men remain the group most at risk of infection in the UK.

Overall, HIV infections have declined over the past four years but campaigners say testing and condom use needs to be “normalised”.

A total of 6,630 people were newly diagnosed with HIV in 2009, of which 2,760 were gay and bisexual men. In 2008, 2773 gay and bisexual men were diagnosed with the virus.

The overall number of diagnoses is lower than in 2008, but this is due to a decrease in the number of people who were infected overseas, as the number of people who caught HIV in the UK (3,730) was close to 2008’s figure.

HIV campaigners said it was worrying that one in six HIV-positive gay and bisexual men appeared to have caught the infection a few months before being tested. This, they said, points to high ongoing rates of transmission in the gay community.

In addition, more than half (54 per cent) of the total number of people infected began treatment late.

It is estimated that 85,000 people in the UK have HIV but but a quarter are unaware they are infected. London, Brighton and Manchester have the highest rates of diagnoses and estimated infections.

The figures come shortly before World AIDS Day, which is on December 1st.

National AIDS Trust and the Terrence Higgins Trust said the figures showed that HIV infections remain high and prevention must be the focus.

They argued that testing of HIV and the use of condoms needed to be “normalised”.

Sir Nick Partridge, Terrence Higgins Trust’s chief executive, said: ”Far too many gay men are getting HIV. We have to reinforce the community norm that condoms are anticipated, expected and used every time. The decrease in new HIV diagnoses last year shows that we can drive down new infections, and that it takes the whole community working together to achieve this.

“The figures also show more gay men are coming forward for testing than ever before and that we are testing much more regularly than the general population. But, with one in four gay men with HIV remaining undiagnosed, we need to make regular testing for HIV-negative gay men an expected part of safer sex.”

Deborah Jack, chief executive of National AIDS Trust, added: “The latest HIV figures underline the need for us to do more in both HIV prevention and HIV testing. As the government prepares its public health white paper, NAT is calling for commitment to reduce the continuing stubbornly high numbers of people getting HIV in the UK. Prevention is an immensely cost-effective activity given the financial implications of even one HIV transmission is up to £360,000 in direct costs to the NHS over a person’s lifetime.

“Another crucial step is for sexual health clinics to work on increasing the uptake of HIV tests amongst those who attend their services. The current uptake rate at 77 per cent is still too low. But late diagnosis is a wider challenge to society – many people with HIV attend other NHS services repeatedly for years without being offered an HIV test and this neglect has to end. We need HIV testing to be normalised within our health system and people to be informed about the value of having an HIV test.”