Brits say they have been sent Fit to Fly certificates by a company listed on the government's website - despite never taking a coronavirus test.
Separate would-be travellers have told The Mirror how they had to cancel their appointments with DAM Health, which advertisers itself a "a leading provider in the UK for Covid-19 Testing solutions."
Days later they received Fit to Fly certificates from the company, declaring them free of the virus and able to jet off abroad.
The mistake has raised serious questions about the reliability of private firms offering coronavirus tests, which are kept at arms length by the government that does not "endorse, recommend or approve any private test provider", despite being listed on its website.
Jean Macintyre was due to fly out to Portugal with nine friends only for her brother and sister-in-law to test positive for coronavirus after visiting her in Preston.
She emailed DAM Health cancelling her appointment on June 1 which she did not attend as she was in isolation.
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Two days later she received a negative test result from DAM Health in a letter signed by Professor Franklin Joseph, the global medical director of the company and a diabetes specialist.
"A Fit to Fly declaration means that Jean MacIntyre has tested NEGATIVE for COVID-19 at the date & time of the test," it read.
"I thought it was fairly remarkable to be honest," Jean told The Mirror.
"I phoned them and a woman told me it was an admin error. Another person on the phone when I called two days later says sometimes the computer auto generates certificates.
"I now question the validity of the other nine results.
"It is a money making industry. If it's not illegal it's immoral.
"I could have had Covid, my brother and sister both stayed with me and had it. I could have gone on a plane to Portugal with nine other people.
"Who is actually monitoring these companies? it is irresponsible. I could have officially gone and contaminated go knows how many people."
A man, who asked to remain anonymous, also told the Mirror that he had received a negative fit-to-fly certificate after cancelling his test.
A Department of Health and Social Care spokesperson said that all commercial test providers of sample collection and/or test analysis must undertake a three-staged UKAS accreditation process to ensure standards are high.
“While we do not endorse or recommend any private Covid-19 testing provider, we are clear that all private providers must meet the minimum required standards," they added.
“Each provider is reviewed by the independent United Kingdom Accreditation Service (UKAS), and the department carefully monitors issues raised by the public and we raise complaints with private test providers directly.
“Organisations can be taken off the lists if they are found to be non-compliant with any of the minimum standards, are not meeting their accreditation deadlines or have been raised as a possible public safeguarding risk to the department.”
A DAM Health spokesperson said: "We have now launched a full internal investigation into the matter and are taking appropriate action to ensure it does not happen again.
"DAM Health are part of the UK’s growing Covid testing sector which offers a range of tests for a variety of reasons, including travel and business.”
