Foreign nationals are to be offered free treatment for HIV on the NHS under plans backed by the government.
Campaigners say the move in England will reduce the risk of Britons being infected and cut the costs of more expensive later treatment.
Currently only British residents are eligible, which excludes migrants.
The Department of Health said it would bring England into line with Scotland and Wales, and there would be safeguards against "health tourism".
There are an estimated 25,000 people with undiagnosed HIV in Britain, many of whom were born abroad.
People from overseas cannot be treated for the condition unless they pay, which is not the case for other infectious diseases.
This group of people includes failed asylum seekers, students and tourists.
Conservative former cabinet minister Lord Fowler, who headed the government's Aids awareness campaign in the 1980s, has called for an amendment to the Health and Social Care Bill currently before the Lords.
This would extend free treatment to those who have been in Britain for six months.
The proposal will be introduced by the government in a Statutory Instrument rather than as part of the legislation.
Public Health Minister Anne Milton said: "This measure will protect the public and brings HIV treatment in to line with all other infectious diseases. Treating people with HIV means they are very unlikely to pass the infection on to others."
Yusef Azad, director of policy at the National Aids Trust, said: "If someone is tested and treated early, it is much cheaper than them presenting themselves in hospital with a much more serious, complex condition that can cost tens of thousands of pounds to treat."
Professor Jane Anderson, chairwoman of the British HIV Association, said: "This is good news for people living in the UK who are HIV positive and also for public health in general."
Critics claim the decision could prompt so-called health tourism and put the NHS under further financial pressure.
But the government pledged tough guidance to ensure the measure is not abused.
The Department of Health said it would be difficult for somebody to come to the UK specifically for treatment as the process took months to administer and monitor.