Roche said a move to a new warehouse had caused a “very significant” drop in its processing capacity. As well as diagnostic tests, the company supplies the UK with diabetes tests, magnesium level tests, and supplies for blood gas analysers, which are also affected by the disruption.

A company spokesperson said the problems could take weeks to rectify, but that Roche would prioritize Covid-19 tests. “We deeply regret that there has been a delay in the dispatch of some products,” it added. “We are prioritizing the dispatch of Covid-19 PCR [diagnostic] and antibody tests and doing everything we can to ensure there is no impact on the supply of these to the NHS.”

This latest blow for Britain’s NHS Test and Trace program comes just days after it was revealed that thousands of Covid-19 cases went unreported due to a huge IT blunder.

British Health Secretary Matt Hancock admitted on Monday that the use of outdated data formatting in an Excel spreadsheet resulted in 15,841 cases of the virus being missed between September 25 and October 2.

The problems with Roche supplies began to emerge a week ago, according to Allan Wilson, head of the Institute of Biomedical Science, the leading international professional body for scientists.

Dr Tom Lewis, lead clinician for pathology at the North Devon District Hospital, in the southwest of the UK, told the BBC that his NHS trust had advised doctors to halt all non-urgent blood tests in the area.

The doctor warned that the hospital would run out of swabs in “three to four days” if the trust didn’t take action.

Following the UK’s days of confusion over testing, health officials reported a further 14,162 coronavirus cases on Wednesday, bringing the total to date to 544,275.