In a letter to prime minister David Cameron, Marcus Agius - who is also the chairman of Barclays - claimed British financial firms are losing ground to overseas rivals as a result of recent banking reform, This is Money has reported.
"There are many areas where the UK stands alone or in a very small minority in implementing agreements reached to date," he explained. "This is not always to the UK's advantage."
Mr Agius urged Mr Cameron to put pressure on fellow world leaders to bring their own financial sectors into line and implied that some countries have adopted a protectionist attitude to the post-recession regulatory overhaul.
His comments came as Barclays announced its third-quarter profits fell by 76 per cent following a drop in income.
By Asim Shah