HIV testing should be made readily available at "GPs surgeries" and other "community settings" in a bid to tackle rising numbers of carriers who do not know they are infected, a group of experts has warned.
In a letter to mark World Aids Day, the coalition describes the level of undiagnosed HIV as "a huge public health issue".
The letter comes after the Health Protection Agency (HPA) revealed last week that 28% of people with HIV (more than 21,000 individuals) do not know they have it.
The HPA has called for new national testing guidelines with wider HIV testing in areas of the country where prevalence of the infection is greatest. It adds that men and women aged 15 to 59 should be offered an HIV test when they register with a GP or are admitted for treatment.
The letter, from MPs and charities, states: "Undiagnosed people are unaware of the specific risk to their sexual partners and so may not consistently use a condom; and since they are not on treatment, they are also likely to be more infectious.
It added: "Testing needs to be easy to access, not just in GUM clinics, but in GPs surgeries and in community settings accessible to high-risk populations.
"The government needs to encourage the NHS in other parts of the country to act similarly to tackle undiagnosed HIV."