The accusations were made following an investigation by the International Consortium of Investigative Journalists (ICIJ) into data supplied by a former IT employee of HSBC's Swiss private bank, Herve Falciani, who downloaded details of accounts and clients at the end of 2006 and early 2007.

The allegations include claims that HSBC marketed schemes which were likely to enable wealthy clients to avoid European taxes and claims that the bank helped some to conceal undeclared accounts from domestic tax authorities.