Global banking giant HSBC on Friday said it had launched a review on whether to remain headquartered in Britain as the country tightens regulation of the sector.

In a surprise announcement less than two weeks before Britain's general election, the Asia-focused bank again highlighted its concern about government policy to ring fence British banks' retail operations to protect them from their investment divisions.

The board has "asked management to commence work to look at where the best place is for HSBC to be headquartered" amid "regulatory and structural reforms", HSBC chairman Douglas Flint was to tell shareholders at the group's annual general meeting taking place Friday in London, a company statement said.

"The question is a complex one and it is too soon to say how long this will take or what the conclusion will be; but the work is underway," Flint was to add.

HSBC, founded in Hong Kong and Shanghai in 1865, employs thousands of workers at its London headquarters.

"As I said at our informal meeting in Hong Kong on Monday, we are beginning to see the final shape of regulation and of structural reform, including the requirement to ring fence in the UK," said Flint's speech.

"As part of the broader strategic review taking place, the Board has therefore now asked management to commence work to look at where the best place is for HSBC to be headquartered in this new environment."

Flint insisted that "the global financial system is transparently and markedly stronger than it was before the (2008 financial) crisis and it is essential we are able to utilise this strength to support risk taking and entrepreneurial ambition within the communities we serve".