Emails from HM Revenue & Customs requesting taxpayers' bank or credit card details in order to receive a tax refund is part of a criminal scam, warns the department. HMRC said it never contacts customers via email for confidential details in these sorts of circumstances. Lesley Strathie, HMRC chief executive, said: 'We only ever contact customers who are due a refund in writing by post. I would strongly encourage anyone receiving such an email to immediately send it to us for investigation and delete it from their computer.' The online attacks are known as 'phishing' and HMRC is already acting to catch the culprits by cooperating with law enforcement agencies in the UK and overseas in places such as Korea, Thailand, the UK and US where a number of scam networks have been shut down.