Compulsory HIV and TB tests for asylum-seekers and other immigrants would be expensive and drive sick people underground, Tony Blair's favourite think-tank has declared.

A research paper published by the Institute for Public Policy Research (IPPR) argues that health screening for asylum-seekers at ports of entry could create more problems than it solves. The study comes as the Government prepares to produce controversial plans this year for the screening of migrants to the UK for Aids, HIV, TB and other diseases.

Downing Street announced nearly a year ago that it was setting up a cabinet-led interdepartmental working group on imported infections and immigration. The review's conclusions and recommendations are expected soon, but the study suggests that migration requires a more sophisticated public health policy based on evidence about an increase in the occurrence of the diseases.

The report, by Dr Richard Coker, a public health specialist at the London School of Hygiene and Tropical Medicine, examines the medical, legal and ethical issues surrounding entry and pre-entry screening. Dr Coker concludes that screening is ineffective, costly and may have detrimental impacts on public health.

He suggests that the public is being misled about the benefits of introducing health screening for migrants and asylum seekers. He recommends instead that the Government introduces a "welcome health check" for all migrants after they enter the UK.

Additional resources should also be directed to providing better health care in countries of origin to prevent the global spread of TB and HIV. The Government has for several months been examining ways to tackle the situation, and has looked at systems in Canada, Spain and Australia.

Opponents of compulsory checks point out that TB tests on about 5,000 asylum-seekers screened under a pilot Home Office project in Kent last year failed to find one refugee with an infectious disease. Just three of those tested were regarded as suspect cases. Further checks indicated that the infection would be neither active nor dangerous to others.

The results from the experiment, which began in 2002, will encourage doctors and others dismayed by recent suggestions that immigration threatens to engulf Britain with "imported" epidemics.

The all-party parliamentary group on Aids warned last summer that mandatory tests would breach the UK's human rights obligations and increase health risks by deterring immigrants already in the country from being tested.

Heaven Crawley, associate director at the IPPR, said compulsory screening of asylum seekers for TB and HIV would have only a slight impact on the spread of those diseases. She said: "Screening for TB is ineffective and compulsion may push those carrying infectious disease underground.