The number of scam calls dropped when lockdown began at the end of March with the percentage of nuisance calls made to UK homes as a proportion of total calls much lower than the usual average of 37% a month.

But now call centres – including those run  by scammers – are set to open again, the number of nuisance calls is set to rise.

National Trading Standards found that Covid-19 provided new opportunities for telephone scammers to take advantage of members of the public.

One company was found to have made more than 680,000 automated scam calls over a four-week period, urging people to purchase face masks and hand sanitiser at a cost of £29.99 to £49.99 by falsely claiming that the PPE was a government requirement.

To coincide with the expected surge in telephone scams, National Trading Standards is offering 700 free call blockers on a first-come-first-served basis for households looking to prevent nuisance calls.

A survey by National Trading Standards found that 92% of call blocker users no longer received scam or nuisance calls within three months of call blocker installation, with 95% of users no longer feeling threatened or scared by these types of calls.

The free call blocker units supplied are  trueCall Secure call blockers – the same devices that have been used in previous National Trading Standards pilot programmes.

Louise Baxter, head of the National Trading Standards scams team, says: “Scam callers are relentless and often leave their intended victims feeling scared, anxious and unsafe in their own homes.

“Our pilot call blocker schemes have already shown the effectiveness of call blockers in protecting households from potential scams and the distress that these types of calls can cause. This technology can make a real difference to the quality of life and emotional wellbeing of people who are targeted by nuisance or scam calls.”

John Whittingdale, media and data minister, says: “We are determined to end the plague of nuisance calls ruining elderly and vulnerable people’s lives. It’s fantastic to see Trading Standards help block unwanted calls as lockdown lifts.

“By providing 700 call blockers free of charge we can continue to drive down nuisance calls and reduce the emotional distress they cause.”

Anyone who feels threatened by scam and nuisance calls can apply for a free call blocker from National Trading Standards. Devices can be self-installed.