A hospital consultant is calling for widespread HIV testing for accident and emergency department patients.
Dr Kaveh Manavi, a consultant in HIV medicine at Birmingham's Selly Oak Hospital, told the BBC everyone should be tested unless they opted out.
He said the current system, which targets high-risk groups, such as gay men and drug users, missed many people.
HIV charity the Terrence Higgins Trust says targeted testing by GPs and clinics would be more cost effective.
Dr Manavi told BBC Radio Five Live the current testing system failed to pick up many adults outside the key targeted groups who were at risk of infection.
He said studies suggested a fourth of patients infected with HIV were diagnosed late and that the target-based HIV tests were not tackling these figures.
"Target-based HIV tests - offering the test to intravenous drug users and gay men - is not going to work because individuals may not identify themselves as a risk," he said.
"All the current data suggests a large proportion of patients, in the UK at least, are heterosexual, so we will miss a proportion of HIV-infected patients."
Dr Manavi wants to see wider screening so that more patients are diagnosed early.
They could then be offered better treatment as well as given the option of altering their behaviour to cut the risk of passing on the virus, he said.
Such widespread screening is already carried out on pregnant women who are routinely checked to reduce the risk of passing on the virus to their babies.
"Early diagnosis of HIV has got advantages for patients," said Dr Manavi.
"It will prevent them from developing AIDS and it will prevent them from transmitting infection to other individuals."
He added: "The sooner an individual is diagnosed with HIV, the higher their likelihood of a better prognosis."
But the Terrence Higgins Trust, said that rather than blanket-testing, it would be much more useful if GPs and family planning clinics conducted the tests because they had a "better idea of whether their patients are sexually active".
Lisa Power, the charity's head of policy, said: "We don't disagree with this doctor about the need to better diagnose HIV.
"We're just questioning whether blanket testing in accident and emergency would be the best way of spending the limited amount of money that the NHS has."
One person in three who are HIV do not know they have the virus while others who have been at risk refuse a test because of the stigma associated with the virus, said Ms Power.
She said ways other than blanket-testing needed to be found to tackle these issues.
A Department of Health spokeswoman said it was committed to reducing the number of HIV cases, particularly in high-risk groups, "through screening, more frequent testing and targeted campaigns".
"Reducing undiagnosed HIV is a priority of the Department of Health which is why genito-urinary medicine clinics offer all first-time attendees an HIV test with follow-up testing for those in high-risk groups," she said.
She also pointed out that the "vast majority" of HIV infections found in the UK are in gay and bisexual men and amongst African communities.