The tax authority has said households with a landline number should be vigilant if they suspect phone calls from fraudsters pretending to be the tax authority.

HMRC says it received more than 60,000 reports of phone scams in the six months up to January - an increase of 360% compared to the previous six month period.

Pensions cold calling was made illegal on 9 January with scammers facing fines of up to £500,000. It's not yet known if the latest wave of cold calls includes pensions-related calls or other investments.

Elderly and more vulnerable people are increasingly being targeted, says HMRC. Some 26m people in the UK have a landline.

During the last 12 months, HMRC has worked with the phone networks and Ofcom to close nearly 450 lines being used by fraudsters using boiler room tactics to steal money.

HMRC says that because of crackdowns on email and SMS phishing, a “rising number of criminals” are turning to the traditional method of cold-calling publicly available phone numbers to steal money from taxpayers.

Financial Secretary to the Treasury, Mel Stride MP, said: “We have taken major steps to crackdown on text and email phishing scams leaving fraudsters no choice but to try and con taxpayers over the phone.

Head of Action Fraud Pauline Smith said fraudsters were calling individuals and claiming to be from reputable organisations such as HMRC. Scammers often tried to convince people to hand over personal details or transfer cash, she said.