Prime minister David Cameron has refused to back Bob Diamond following the Barclays market manipulation scandal, as Labour leader Ed Miliband called for the bank boss to go.
Cameron refused to back Diamond when asked if he was the right person to run the bank, telling journalists: "I can't say that. As I say, he has got questions to answer."
The prime minister, speaking during a press conference on Friday said Diamond had "some serious questions to answer".
"People are rightly angry about the behaviour of the banks and so am I," Cameron said.
"I know that Bob Diamond has quite rightly agreed to appear before the Treasury select committee. As I said yesterday, he and his management team have serious questions to answer."
Barclays was fined £290 million by UK and US regulators for manipulating the rate at which banks lend to each other, and echoes the costly payment protection insurance (PPI) mis-selling scandal that emerged last year.
Banks are facing the threat of a criminal investigation over fixing the interbank lending figures that affect millions of homeowners and small firms.
Labour leader Ed Miliband, meanwhile, has demanded an inquiry into the banking industry, saying "I think its pretty clear the change that is required at Barclays."
"We definitely need an inquiry into the culture and practices of the industry.
"What's been revealed with Barclays is a set of practices which have appalled people across the country and we've got to make sure we shine a light in all the corners of the industry to find out why these practices have been going on and what it is about the culture that has enabled this to happen," Miliband told journalists on Friday.
"I am calling for change at Barclays. It's obviously a matter for the shareholders in the end but I think that it is very hard to see how the current leadership, who were there when some of these things were going on, can bring about the changes required."
In a further blow, the Financial Times called directly on the senior banker, who it said was behind the bank's "hard-driving culture", to step down.
"If he had an ounce of shame he would immediately step down," the newspaper said in a front page editorial.
However, Diamond remains bullish about his ability to stay in the role, vowing to fight on.
The leaders' comments came as Bank of England governor Sir Mervyn King lambasted British banks and called for a "real change in culture" as lenders became further embroiled in controversy.
"Something went very wrong with the UK banking industry and we need to put it right," Sir Mervyn said.
His intervention came as a fresh mis-selling scandal involving complex financial products added to the anger surrounding the rate-rigging affair uncovered at Barclays earlier in the week.