Tessa Jowell, the Health minister, will announce today that HIV screening is to be made available at every ante-natal clinic in the country, The Independent has learnt.
Ms Jowell will unveil the plans, to take effect within weeks, as a key part of her department's attempt to prevent the transmission of the illness.
Ministers decided to act after figures showed that the UK had one of the highest maternal HIV transmission rates in Europe, and one of the lowest identification rates among pregnant women.
Of the 265 HIV-infected women who give birth every year, up to 50 babies are born with the virus, mainly because their mothers are unaware that they are infected.
Ms Jowell's announcement will implement the recommendations of a group set up three months ago to find ways of reducing the problem.
The screening scheme, which will not be compulsory, will be available to all and will be offered alongside blood tests and other examinations currently offered.
There will also be measures to help those women who find they are carrying the virus.
Anti-retroviral drug courses will be offered during pregnancy, along with careful obstetric management and Caesarean sections. Once born, the babies should be bottle fed rather than breast fed. The combination of drugs, Caesareans and bottle feeding reduces the chances of HIV transmission from one in six to one in 100.
Ms Jowell said: "With 50 babies born a year with HIV, it is tragic that most of their mothers don't know they have the virus before they give birth. In the majority of cases, transmission can be prevented once HIV is identified.
"There is no question of this being compulsory, but frankly what woman, who may have lingering doubts, is going to turn down a test which would make all the difference in the world to ensuring the right treatment?"
The scheme, which will also be accompanied by targets for numbers of women screened per year, follows similar projects in France and the United States, where mothers to be are routinely tested for HIV.
Britain has one of the highest rates of HIV among children and teenagers in the West.
Only a handful of clinics across the country currently offer an HIV screening service and the expert group, which was made up of paediatricians and public health officials, suggested that a comprehensive system should be created. The HIV blood test is simple and relatively cheap to carry out.
Anonymous surveys by the Department of Health found 195 cases of pregnant women with the virus in London, 56 in the rest of England and Wales and 14 in Scotland. Of those, 40 babies were born with the virus in London and 12 elsewhere.
London is the highest risk area, partly because of its large and cosmopolitan population, and a high number of drugs users. Glasgow, however, is seen as a "high prevalence" region due to widespread intravenous drug use.
While the scheme to be announced today only covers England, ministers hope it will be extended throughout the UK under powers devolved to the regional assemblies.
Fears about the levels of ignorance were confirmed when researchers found that in more than 70 per cent of cases the condition was undiagnosed until the baby was born.
The UK's HIV infection rates for adults are average for Europe, but the rate for mother-to-baby transmission is among the highest on the continent. Most worrying of all, the expert group found that while the number of Aids-infected babies under 12 months was dropping across the EU, it was rising in the UK.
Although anti-viral drugs are having some success, most children with HIV do not live beyond their teens.
Last night, a health department spokeswoman stressed that the tests were totally confidential and could not be released to insurance companies without a patient's consent.
The Government is due to publish a comprehensive HIV/ Aids strategy early next year.