The head of an influential committee of MPs has called for the chair of the BBC Trust to resign or be sacked from her role overseeing the corporation over her role as an independent director at scandal-hit bank HSBC.
Margaret Hodge, chair of the Public Accounts Committee, said that Rona Fairhead, who chaired the audit committee of the bank, had been "either incredibly naive or totally incompetent".
Hodge said: "I don't think that the record that you have shown of your performance here as the guardian of HSBC gives me the confidence that you should be the guardian of the BBC licence fee payers' money.
"You should think about resigning. If not, the Government should sack you."
Fairhead was being grilled by MPs on the committee over her oversight of the bank, which has come under fire over claims that its Swiss private banking arm helped clients avoid millions of pounds in tax.
The same hearing also saw the bank's chief executive Stuart Gulliver forced to defend his own position while Chris Meares, former group head of private banking, was accused of being an "unreliable witness".
Fairhead "categorically" denied knowing about the Swiss tax scandal at the time and said that she had been "unyielding" in acting against wrongdoing.
She said: "I think that first and foremost the people who are most culpable are those people who evade taxes."
Fairhead also pointed the finger of blame at "frontline" staff for breaching the policies of the bank.
She added: "We were horrified when we discovered. I can assure you absolutely no evidence of tax evasion was received. I could only respond to evidence that I had and I could only deal with that."
But Hodge said for a highly-paid non-executive to "simply take the evidence and not question, to me would mean she is not fit for purpose".
Fairhead described as untrue reports that she is paid £10,000 a day by the bank.
HSBC's annual report showed she received £513,000 in fees and benefits last year including a £334,000 fee as non-executive chairman of HSBC North America Holdings.
One MP, Austin Mitchell, said her pay seemed like "money for jam".
Fairhead said she worked 75 to 100 days a year including weekends for the bank, plus 150 to 180 days for the BBC, as well as 25 days in a separate role for Pepsi.
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