"We continue to keep our UK domicile under review," Chairman John Peace told investors at the group's annual general meeting in London, ahead of a knife-edge election fought largely over the economy.
"Although we have no current plans to leave our domicile, we are listening carefully to our shareholders views on this issue," he added.
Peace indicated that the two main factors for the bank were the nation's regulatory landscape and bank levy.
Some shareholders are reportedly pushing for the lender to switch its base to Hong Kong or Singapore.
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British Prime Minister David Cameron's Conservative- Liberal Democrat government introduced the banking levy -- imposed on lenders' balance sheets -- after it rose to power in 2010. It has since hiked it eight times, most recently in April.
Rival bank HSBC is also reviewing its British base, citing also tighter regulation and rising taxes, and revealed yesterday that it would decide by the end of the year.
The bank highlighted its concern about government policy to ring fence banks' retail operations to protect them from their investment divisions.