THE Scots-born chairman of Britain's biggest bank has hinted it is considering relocating its headquarters abroad.

Douglas Flint, chairman of HSBC, said a review of its head office location was imminent as regulatory changes introduced by Westminster became clearer.

The bank has been in based in London since 1993 when it took over the Midland Bank, but was founded in Hong Hong in 1865 and still has extensive operations there.

The bank has traditionally reviewed its head office location every three years, but has delayed the next review indefinitely in the face of regulatory changes being introduced by the UK's coalition government.

Speaking to Hong Kong shareholders who questioned whether the bank should remain in London, Glasgow-born Mr Flint said: "We are beginning to see the final shape of regulation, the final shape of structural reform and as soon as that mist lifts sufficiently, we will once again start to look at where the best place for HSBC is."

Mr Flint's comments, first reported by Bloomberg, came as investors prepare for the bank's annual meeting in London at the end of the week.

The bank - along with others based in the UK - is being required to ringfence its high street business from its investment banking operations to comply with the reforms set out by Sir John Vickers in his review of banking.

The bank's shareholders are said to be questioning why it has its headquarters in Landon because of Chancellor George Osborne's bank levy, which cost HSBC £750 million last year. To comply with global rules, banks such as HSBC are also being required to hold more capital.

Both the Labour and Conservative parties have pledged a tougher tax regime for banks in their manifestos for the General Election.

Standard Chartered, another bank headquartered in London, but with much of its activities outside the UK, is also facing questions from shareholders.

Richard Buxton, head of equities at Old Mutual Global Investors, said: "There is a very clear risk that HSBC and StanChart reach a pain threshold where they think it is no longer worth staying in the UK."

Meanwhile, HSBC's bosses also used the Hong Kong meeting to apologise to shareholders for activities in the bank's Swiss operations.

Stuart Gulliver, the bank's chief executive, apologised for its conduct following revelations that it had assisted customers in dodging taxes.

The publication of leaked files about the accounts of customers of HSBC's Swiss banking arm between 2005 and 2007 has put pressure on Flint and Gulliver, who have both appeared before committees of MPs to explain the tax avoidance advice that was offered.

Flint could be replaced as chairman in the coming years by one of the new non-executives that the bank is currently recruiting to overhaul its board. The bank has promised shareholders it will break with tradition and appoint its next chairman from outside its ranks.

Last month, Nigel Wilson, chief executive of Legal and General, warned that further increases in bank levy could spark an exodus from London.

Legal and General is the sixth largest holder of Standard Chartered shares and has the fifth largest stake in HSBC.

Mr Wilson's warnings came as Stuart Adam of the Institute for Fiscal Studies said: "At some point, the environment becomes so unfavourable that everyone shifts wholesale to somewhere else."