One of the City's leading figures has suggested that inequality created by bankers' huge salaries is a price worth paying for greater prosperity.

In remarks that will fuel the row around excessive pay, Lord Griffiths, vice-chairman of Goldman Sachs International and a former adviser to Margaret Thatcher, said banks should not be ashamed of rewarding their staff.

Speaking to an audience at St Paul's Cathedral in London about morality in the marketplace last night, Griffiths said the British public should "tolerate the inequality as a way to achieve greater prosperity for all".

He added that he knew what inequality felt like after spending his childhood in a mining town in Wales. Both his grandfathers were miners who had to retire from work through injury.

With public anger mounting at the forecast of bumper bonuses for bankers only a year after the industry was rescued by the taxpayer, he said bankers' bonuses should be seen as part of a longer-term investment in Britain's economy. "I believe that we should be thinking about the medium-term common good, not the short-term common good ... We should not, therefore, be ashamed of offering compensation in an internationally competitive market which ensures the bank businesses here and employs British people," he said.

Griffiths said that many banks would relocate abroad if the government cracked down on bonus culture. "If we said we're not going to have as big bonuses or the same bonuses as last year, I think then you'd find that lots of City firms could easily hive off their operations to Switzerland or the far east," he said.

Goldman Sachs is currently on track to pay the biggest ever bonuses to its 31,700 employees after raking in profits at a rate of $35m (£21m) a day.

The Centre for Economics and Business Research (CEBR) said today that City bonuses could soar to £6bn this year.

The chairman of the Financial Services Authority (FSA), Lord Turner, who was also present at the meeting, called once again for a global tax on financial transactions. He said that such a so-called "Tobin tax" could redistribute bank profits to help fight world poverty and climate change.

"The role of regulation is to bring a concordance between private actions and beneficial results," he said.