Downing Street has said it is “highly unlikely” that the NHS Covid app is leading to large numbers of people being “pinged” through the walls of their home.

A report in the Telegraph said neighbours have been told to self-isolate because the contact tracing app has registered them as a close contact with a positive coronavirus case next door, despite not coming into face-to-face contact.

But No 10 said the app’s signal is unlikely to be strong enough to make such connections.

The app sent 530,126 alerts in England and Wales during the first week of July, and industries are complaining of workforce shortages due to the number of people being told to quarantine.

The app uses low-energy Bluetooth and its signal strength is significantly reduced through things like brick walls

While it is only guidance, users who receive an alert to self-isolate by the NHS app are recommended to follow the advice to prevent spreading the virus.

Asked about the possibility of neighbours being pinged through shared walls, a spokesman for the Prime Minister said: “We’re confident that that is not contributing to large numbers of individuals being asked to self-isolate.

“The app uses low-energy Bluetooth and its signal strength is significantly reduced through things like brick walls, so therefore it is highly unlikely that through brick walls would lead to an alert.”

No 10 said it would “keep under review” the sensitivity of the app but said the technology is doing “what it is designed to do” in alerting people to positive cases.

“It is designed to detect people you’ve been in close proximity to, it is designed to flag to you if they have received a positive test result,” said the spokesman for Boris Johnson.

“That’s what it is designed to do, and that’s what it is doing.”

With Covid cases soaring in the UK, with almost 50,000 cases being recorded daily, Downing Street said more people are expected to be asked to self-isolate.

“The Prime Minister has spoken about the fact that we are seeing case numbers increase, and obviously as a result you would expect to see the numbers of people being notified to self-isolate increase also,” said Mr Johnson’s spokesman.

He said the Government would “not speculate” on whether it had predictions for how many people could be asked to quarantine at the peak of the current wave of infections.