Ministers have been urged against introducing mandatory HIV tests for every immigrant arriving in the UK.
Ministers are considering testing all new immigrants for HIV
The Institute for Public Policy Research, a leading left-wing think tank, says such a move could create more problems than it would solve.
In a report, it warns that testing immigrants could force those most in need of healthcare underground.
A decision on whether mandatory testing should be introduced is expected shortly, after a year-long review.
The review was prompted in part by figures which show that most new cases of HIV in the UK are diagnosed in people who came to the country from abroad.
According to the Health Protection Agency, two out of three heterosexuals who are now diagnosed with the disease contracted it in Africa.
Reports have suggested that ministers have already come down in favour of testing all immigrants and asylum seekers for HIV and other diseases, like tuberculosis, when they arrive in the UK.
The move would bring the UK in line with other countries like Australia and Canada, where everyone seeking permanent residence is screened for HIV.
But in its report, the IPPR says mandatory screening is ineffective, costly and may have negative rather than positive impacts on public health.
It suggests that the public are being misled about the benefits of introducing the tests.
The report, which was written by Dr Richard Coker of the London School of Hygiene and Tropical Medicine, urges ministers to introduce a "welcome health check" after they arrive in the UK.
It says extra money should also be used to prevent the spread of HIV and TB abroad.
"The compulsory screening of asylum seekers for TB and HIV which is being proposed by some will have a limited impact on the spread of these diseases because screening for TB is ineffective and compulsion may push those carrying infectious disease underground," said Heaven Crawley, associate director of the IPPR.
"There are also ethical and moral implications of returning those diagnosed with HIV back to countries of origin.
"The public association between infectious diseases and immigration is a powerful one and is at the heart of many wider concerns about the impact of migration on Britain.
"The government should avoid the temptation of introducing compulsory screening in order to cool the political heat on this issue because the evidence about the positive benefits of such policies is weak."
A spokesman for the Department of Health said the government was still considering the issue.
"The Cabinet Office is currently co-ordinating work between relevant government departments, including the Department of Health, to review immigration and infectious diseases and access to NHS services," a spokesman said.
"The review aims to establish the facts about health and public expenditure impacts and propose solutions should action be required."