A supply chain failure may mean patients will be unable to access key NHS tests for conditions ranging from coronavirus to cancer.
Swiss pharmaceutical firm, Roche - one of the main suppliers of diagnostic testing equipment and materials in the UK - has said that a "very significant" drop in capacity has been caused by a move to a new warehouse. The backlog created may affect tests for a number of conditions, including heart disease and cancer.
A spokesman for the company said that, while Covid-19 tests would be prioritised, it could take two weeks to fix the problem.
GPs urged to halt non-urgent blood tests
In a statement, Roche said, "We deeply regret that there has been a delay in the dispatch of some products.
"We are prioritising 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."
The company didn't comment on the potential impact on other tests for conditions like sepsis or kidney disease.
The Sussex warehouse affected is the company's only distribution centre.
In response, one NHS expert has already advised GPs to halt all non-urgent blood tests.
Dr Tom Lewis, lead clinician for pathology at North Devon District Hospital, told the BBC that his hospital's trust had asked all non-urgent blood tests in the community to stop. Without rationing, he said, they would run out of swabs in around three to four days.
Even with rationing, however, essential equipment may run short as soon as next week.
'Shortage could have considerable impact'
President of the Institute of Biomedical Science Allan Wilson told the BBC that if the problem lasted "days it probably will have minimal impact, but if it's weeks then yes it could have a considerable impact on our ability to deliver tests," across a whole range of conditions in the UK.
Dr Lewis explained that the shortage of electrolyte tests is the biggest concern, as these are a "key test" for critically ill patients, as well as being used by GPs to check medication is safe.
One virologist in the Midlands revealed in a tweet that Hepatitis C testing kits had not been received at her service.
In a letter sent to NHS trusts, seen by the BBC, Roche said, "In September we moved from our old warehouse to a new automated warehouse capable of much higher volumes.
"However, during the transition we encountered some unforeseen issues and a very significant drop in our processing capacity. Since then we have worked around the clock to prioritise and manage orders as well as increase this capacity".