COVID testing has been suspended at a private laboratory in Wolverhampton after an estimated 43,000 people were given incorrect results.

An investigation was launched into reports of people receiving negative PCR test results after they had previously tested positive on a lateral flow device.

NHS Test and Trace estimates that 400,000 coronavirus test samples were processed through the Immensa Health Clinic lab in Wolverhampton – and an estimated 43,000 people may have been given incorrect results between 8 September and 12 October.

The UK Health Security Agency (UKHSA) said most were in the South West of England.

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It insisted there are “no technical issues” with the lateral flow or PCR tests, adding that other labs are “working normally” and described it as an “isolated incident attributed to one laboratory”, but said all samples are now being redirected to other labs.

Test and Trace is contacting people that could still be infectious to advise them to take another test, while close contacts who are symptomatic will also be urged to get tested.

Samples that would have gone to the lab are now being redirected to others.

Dr Will Welfare, public health incident director at the UKHSA, said: “We have recently seen a rising number of positive LFD results subsequently testing negative on PCR.

He added there is “no evidence of any faults” with the lateral flow or PCR test kits themselves and “the public should remain confident in using them and in other laboratory services currently provided”.

“If you get a positive LFD test, it’s important to make sure that you then get a follow-up PCR test to confirm you have COVID-19. If you have symptoms of COVID-19, self-isolate and take a PCR test,” he said.

Immensa Health Clinic Ltd boss Andrea Riposati said: “We are fully collaborating with UKHSA on this matter. Quality is paramount for us.

“We have proudly analysed more than 2.5 million samples for NHS Test and Trace, working closely with the great teams at DHSC and UKHSA. We do not wish this matter or anything else to tarnish the amazing work done by the UK in this pandemic.”

The Welsh government said it heard last week of reports that a “higher than expected” number of positive lateral flows were resulting in negative PCR tests.

Around 4,000 people in Wales may have been given “inaccurate results” from tests processed at the affected laboratory in Wolverhampton and the majority will have been taken at testing sites across the Gwent and Cwm Taf Morgannwg areas, health minister Eluned Morgan said.

Another centre, this time in Berkshire, advised people to get retested over fears they were wrongly given negative results.

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The official advice comes after some PCR tests at the government-run COVID testing site Newbury Showground resulted in false negatives.

It comes as fully vaccinated people arriving in England from countries not on the red list have been told they can take a cheaper and quicker lateral flow test rather than the PCR version from 24 October.

Transport Secretary Grant Shapps said the switch requires honesty from passengers.

Speaking to Sky News, Mr Shapps was pressed on how lateral flow results will be verified and he said travellers will take a photo and upload it, describing it as “straightforward and pretty quick to do”.

He said: “Like so many laws in this country, we ask people not to do things and put societal restrictions on people.

“We don’t have a policeman on every corner, in every home, to make sure people aren’t breaking the law.”