Several suppliers have been accused of “profiteering” through buying PCR tests at cost price before selling them to travellers with mark-ups of up to £100, reports The i newspaper.

Natalie Kenny, from testing firm BioGrad Diagnostics, told the newspaper that some suppliers were buying tests from her company for £50 and then advertising them at hugely inflated prices to consumers.

Kenny added that she had reported several of these companies to the Department of Health and Social Care (DHSC) and the UK Health Security Agency (UKHSA).

The UK government has admitted that test providers on its online list “may not have full accreditation”.

“The government does not endorse or recommend any specific test provider – you should do your own research about them and their terms and conditions,” warns the government on the webpage.

The UKHSA told The i: “We carefully monitor issues raised by the public, and all private providers must meet the minimum standards so that the public can have confidence in the quality of tests provided.

“Any provider may be removed from gov.uk on a precautionary basis, pending investigation, if they are believed to be putting public safety at risk or not to be meeting the minimum standards.

“We do not endorse, recommend or approve any private test provider.”