The HMRC says it has received thousands of complaints from recipients of emails asking them to supply their financial details electronically in order to claim tax rebates.

Victims run the risk of having their accounts emptied, as well as their personal details sold on to other organised gangs.

Lesley Strathie, chief executive of HMRC, says: ‘This is the most sophisticated and prolific scam that we have encountered. We only ever contact customers who are due a refund in writing by post. I would strongly encourage anyone receiving such an email to send it to us for investigation.’

The HMRC is also warning people of a growing number of telephone scams with fraudsters posing as tax officials arranging rebate payments.

The deadline for tax returns is 31 January, anyone filing a late return could be fined £100.

Tax officials are advising anyone who has received a fraudulent email to forward it unopened to phishing@hmrc.gsi.gov.uk.