Testing kits which were headed to the UK have been found to be contaminated with coronavirus
Key components ordered from overseas for the tests were found to contain traces of the virus earlier this week.
It comes as Britain attempts to ramp up mass testing after capacity appeared to lag behind other major nations, including the US and Germany.
To meet demand and boost production, the government has enlisted private companies to help – with plans for thousands of kits to be made available within the coming weeks.
But in a blow to production one of those suppliers sent an email on Monday to government laboratories in the UK warning that a delivery of “probes and primers” would be delayed because it was contaminated, the Telegraph reported.
Eurofins, which is based in Luxembourg, admitted there had been “an issue” but said other private providers had suffered the same problem.