The CMA is investigating Bradford-based Expert Medicals following claims it has not provided tests and results in a timely manner or at all, has failed to respond to customer complaints and has refused to issue refunds.

The firm, one of the largest providers of PCR tests in the UK, “saw a high number of complaints to Citizens Advice and to the CMA”. It no longer appears on the list of testing providers which self-declare they meet the government’s minimum standards.

Another 19 unnamed test providers have been warned to improve pricing information or risk action. 

“The CMA is concerned that the 19 firms continue to falsely advertise tests at very low prices when they are either not available at that price or include hidden conditions, such as where the tests must be collected from,” it said.

The CMA last week sent an open letter to PCR test providers warning that a range of harmful practices in the sector could breach consumer protection law.

CMA chief executive Andrea Coscelli said: “Millions of people have to buy PCR tests in order to travel. If we find that firms have been misleading customers and failing to provide the service that people have paid for, we stand ready to take action.”

The authority is likely to issue advice to the government on the PCR testing market by 10 September.