Basic products such as hand sanitizer, antibacterial wipes and baby formula are being sold online at “hugely inflated prices”, Which? says.

To help clamp down on so-called price gouging, the consumer group has launched a free tool that anyone can use to report businesses selling products at rip-off prices.

Which? said it will share reports from the tool with the Competition and Markets Authority (CMA) to help establish the scale of the problem and take action against the worst offenders.

The consumer group has received hundreds of reports of unscrupulous sellers taking advantage of the current crisis by charging extortionate prices for products that are in particularly high demand or hard to find on the high street.

Its researchers found a £40 thermometer on sale for £300 and a £3 bottle of disinfectant retailing for £29.99.

It warns vulnerable people are being pressurised into overpaying on sites such as Amazon and eBay for these essentials because of a lack of alternative options.

It said it has also heard numerous reports of price-gouging at bricks and mortar retailers including pharmacies.

Sue Davies, head of consumer protection at Which?, said: “It is unacceptable for people to be left at the mercy of unscrupulous sellers during a national emergency. We’re calling for people to report opportunistic coronavirus profiteers via our tool so that we can press home the need for swift action and put an end to price-gouging on basic goods.

“The government, working with the CMA, needs to step in with emergency legislation to crack down on price-gouging and keep the price of essential items reasonable during a crisis.”

The CMA and Chartered Trading Standards Institute have both raised serious concerns about problems with price-gouging and the Prime Minister has also warned traders against “exploiting people’s need” during a national emergency.