The boss of JP Morgan has met Andy Burnham and John Healey amid fears of a new windfall tax on banks .
Jamie Dimon, who has led the Wall Street lender for more than 20 years, met the Prime Minister and Chancellor in London on Wednesday after a phone call with the latter last month.
It comes just weeks before Mr Healey delivers his first Budget as Chancellor.
He is under pressure to find billions of pounds to repair the public finances after the fallout from the Iran war derailed the Government's plans.
The American banker , who has met many chancellors during his period in charge of JP Morgan, was a strong supporter of Mr Healey's predecessor, Rachel Reeves.
"They are smart and dedicated and they are working with business and collaborating, which is the only way to make things work," he said of the former chancellor and Sir Keir Starmer in an interview with The Sunday Times.
During Ms Reeves's spell as chancellor, she resisted calls to raid lenders for more tax, calling financial services "the crown jewel in the UK economy" and instead encouraged regulators to relax rules in the City.
However, there are concerns that Mr Healey may raise levies on banks in his Budget on Oct 28.
Mr Burnham dropped into a meeting between Mr Dimon and Varun Chandra, the Prime Minister's chief business adviser, according to the Financial Times.
Mr Dimon has previously warned Andy Burnham against the idea. The JP Morgan boss said in an interview earlier this year that there would be "adverse consequences" if Labour targeted lenders with fresh windfall taxes.
He said: "It would be one more negative on that bucket of things you got to think about.
"I always thought it was wrong. We're a great citizen [in the UK]. We hire people there. We want to be bigger there. We train people there. We hire veterans there."
The American banker added: "So if a government decides to do it, there's nothing I can do, but it will over time cause decisions made that they may not like."
There have been growing calls from unions and campaigners to raise taxes on banks .
Paul Nowak, the general secretary of the Trades Union Congress, has argued that Mr Burnham could raise £9bn in four years simply by reversing the previous Conservative government's cut to the bank surcharge. The group has argued that this could be used to fund cuts to energy bills.
The Green Party also recently called for a 38pc windfall tax on banks to fund a tax cut for small businesses.
Jane Fraser, the boss of Citi, another Wall Street bank, has warned that any increase in taxes risks making the UK a prohibitively expensive place to do business.
She said during a visit to London last month that "money moves with its feet", pointing out that "even Frankfurt and Paris are lower" when it comes to taxes for banks.
Mr Healey said this week that "doubling down" on "more growth generated in more places" will be a central priority of his first Budget.
He has refused to rule out raising taxes, but promised to "balance the books" and "control public spending".
