The caller typically claims there are issues with the victim’s internet connection and that they need to gain access to their computer to perform tests and fix it.

The caller asks the target to download the Teamviewer application – this can give the scammer remote access to a computer and potential access to the victim’s personal details, such as banking usernames and passwords.

Katherine Hart, a lead officer at CTSI, said: “The pandemic lockdown has led to record numbers of home workers, corresponding to a surge in internet use both in the UK and the wider world. I am concerned that this kind of scam could catch people off guard; indeed, I know of two individuals targeted by it this month.

“Since the first lockdown last March, fraud networks have used the pandemic as an opportunity to ruin people’s lives further, and I have warned the public about this at every step. We should not merely ignore it – we must report all instances of scams as this provides vital intelligence for the authorities.

“Do not be mistaken that scammers only use the BT brand – they hijack all kinds of internet provider brands to conceal their real intent.”

National Trading Standards warned last week that scam and nuisance phone calls have returned to levels seen before the first lockdown.

In April 2020, when lots of call centres were suddenly closed as a result of restrictions imposed by governments to halt the spread of coronavirus, 10% of calls received by trueCall devices were scam or nuisance calls. By October 2020, this figure had risen to 35%, taking numbers of nuisance calls back up to levels last experienced before the pandemic.