Such tests - which are currently legal and not subject to legislation - might otherwise become a routine way to estimate workers' future absenteeism, it warned.
A study by the Human Genetics Advisory Commission found only one employer which uses genetic tests now, but the practice may become more widespread as the tests become cheaper.
"We have heard expert opinion that genetic testing may become relevant to employment in the future, although it is difficult to predict the time scale," says the commission's report.
Scientists are on the verge of unravelling the entire genetic makeup of mankind as part of the international Human Genome Project, which is leading to the development of a new generation of genetic tests.
In future, employers might try to assess workers' likely illnesses based on a genetic analysis, making the tests a valuable tool for assessing future labour costs.
"Unfair discrimination might arise if employers use genetic test results for employee selection," the report says, concluding that "it would not be acceptable for genetic test results to be used to exclude people from employment or advancement on the grounds that they have a predisposition to future ill health."
The Ministry of Defence is the only employer now using genetic tests - to assess pilots for sickle-cell anaemia, an inherited condition linked with black-outs during depressurisation.
Baroness O'Neill, the acting chair of the commission, said employers would only be justified in insisting on a genetic test if an inherited disorder might pose a risk to others. Train drivers, for instance, are already checked for colour blindness - a genetic trait - though with a conventional test. But other dangerous conditions could only be found by genetic testing.
The commission recommends that for jobs where public safety issues arise, an employer should have the right not to employ someone who refuses a genetic test.Reuse content