England's NHS Covid-19 smartphone app does not accept test results processed in the country's state-run laboratories, hospitals or as part of an official survey, it said on Saturday.
The app's official account said on Twitter it could not link to test results taken in Public Health England (PHE) laboratories, at the National Health Service (NHS) or as part of a survey run by the Office for National Statistics (ONS).
The news prompted disbelief and scorn with one inflamed tweeter writing:
On Friday, 210,375 tests were taken, with 61,481 (29 per cent) handled by PHE and the NHS. That does not include tests taken as part of the ONS surveys because they are counted on a UK basis.
Tests taken in hospitals include patients and healthcare staff.
The app was launched on Friday, following months of delay and questions about its effectiveness in the face of mixed results from other countries which have already deployed such apps.
As the software is voluntary, its success depends heavily on how many people choose to download and use it.
International examples of similar apps show a take-up rate of about 10 per cent to 30 per cent - well short of the National Health Service target of 80 per cent.
“The truth is the more people who get it, the safer we will all be," UK Health Secretary Matt Hancock told the BBC on Friday.
He is also described it as being "dead simple to download."
The app uses Bluetooth signals to log when a user is in close contact with another user, generally meaning within two metres for 15 minutes or more.
If someone then tests positive, they can share the result anonymously with their close contacts who will each receive an alert and will have to isolate for 14 days.
The launch comes as Britain braces for a second wave of infections, with daily cases rising at rates not seen since the peak of the pandemic.
The Department for Health did not give an immediate response but its website said it was working to rectify this issue as soon as possible.
The malfunctioning app is a significant setback to the UK government and opens up its handling of the pandemic to further censure. These seven charts tell the story of Britain's coronavirus travails.