There should be a clampdown on private medical screening, government advisers are set to recommend.
Private companies offer a range of scans
The National Screening Committee is considering how best to regulate the industry, Pulse magazine reports.
It is acting because of fears there are too few checks on the sector - and too much pressure on the NHS.
Tests cost from £10 for a cholesterol check to thousands for a body scan, but people can then be sent to the NHS for further - often unnecessary - checks.
Sir Muir Gray, programme director of the National Screening Committee, said the whole industry would face close scrutiny and tough new regulations.
He told Pulse: "We are thinking of how we control private testing because it's an example of low value activity which generates work for the health service, may cause harm and does not benefit the individual.
"We'll look at different forms of regulation - some from the Healthcare Commission, some through the Advertising Standards Authority, some through the Office of Fair Trading. It will be an evidence-based regime."
He said the current system was failing: "I don't think we've got a proper system of regulation at all for the independent sector.
"Lots of GPs I know are very concerned about people who go to a private clinic for a blood test and then the people who run the private clinic say 'Oh your kidney results look a bit funny - just go and see your GP'."
The Royal College of GPs is backing calls for tougher regulation.
Professor Mayur Lakhani, chair of the RCGP, said: "Screening is becoming increasingly popular and is not without hazard if done in an unprepared way.
"Working to national standards would bring added peace of mind."
Dr Peter Mace, Bupa Wellness' Assistant Medical Director said: "We refute the allegation that health assessments cause patients anxiety. Our experience is quite the opposite.
"We identify a health issue for around a third of customers which they were previously unaware of."
A Department of Health spokeswoman said: "We await the advice of the national screening committee and will consider their recommendations carefully."