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.”