HSBC has given the clearest warning yet that British banks would move their headquarters abroad if the UK government- appointed Commission on Banking were to decide that big groups should be broken up.

Stuart Gulliver, the group’s investment banking head and the favourite to succeed Michael Geoghegan as chief executive, said yesterday he was “genuinely concerned” that the commission would recommend that universal banks, such as HSBC, should split their high street banking from their riskier investment banking activities.

“It is clearly possible that that commission comes up with a recommendation to break up the banks,” Mr Gulliver told a conference sponsored by Nomura, the Japanese bank. “[That] has significant implications clearly for where we may choose to headquarter our institution.”

The comments follow more veiled suggestions from Barclays and Standard Chartered last month that they could relocate to Asia or the US if they were threatened with break-up. HSBC would almost certainly choose Hong Kong as its new headquarters.

In January, HSBC moved its chief executive’s office to Hong Kong but the bank has consistently denied it wants to shift its HQ. “I want to be crystal clear. Our preference is to be headquartered in the UK,” Mr Gulliver reiterated yesterday.

The Commission on Banking was appointed by the coalition government to examine a range of issues in the banking market, including the risks inherent in universal bank structures and competition in retail and business banking. Chaired by Sir John Vickers, the former head of the Office of Fair Trading, the commission is expected to give more detail on its focus by the end of this month.