The list of account holders in HSBC's Geneva-based private bank also includes its chief executive Stuart Gulliver, the bank has confirmed.

The bank made its confirmation in response to a report in The Guardian, which said that leaked files show that Mr Gulliver held millions of pounds in a Swiss account through a Panamanian company. He also held a second account in the name of Worcester Foundation, which had been closed before 2007.

HSBC's statement makes no mention of this Panamanian company, but states that its chief executive uses this account to hold the bonuses he receives.

The Guardian does not suggest wrongdoing on Mr Gulliver's part, and quotes his legal representatives as saying that he has voluntarily declared his Swiss accounts to UK tax authorities. The 55-year-old Briton is registered as a Hong Kong resident for legal and tax purposes, although he is now based in the UK.

Through the Swiss Leaks investigation, the International Consortium of Investigative Journalists released information about bank accounts held in HSBC's Swiss subsidiary HSBC Private Bank (Suisse), based on files stolen by a former staffer and handed to French authorities in late 2008.

The ICIJ claims that the bank has held secret accounts for "criminals, traffickers, tax dodgers, politicians and celebrities."

Just last weekend, Mr Gulliver had signed an apology on behalf of the bank to its customers and staff, in which it said that it has overhauled the way it conducted its business since 2008.