RISHI Sunak today demanded a probe into Nadhim Zahawi's tax affairs - saying there are "clearly questions to answer".
The PM launched the investigation into the embattled Tory Chairman, who is fighting for his political life.
Mr Sunak is also facing pressure over sleaze allegations against his predecessor Boris Johnson.
It was yesterday revealed that the then PM sought help with his finances from ex-banker Richard Sharp - before then supporting his successful application for BBC chairman.
Mr Johnson today branded accusations of cronyism a "nonsense".
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The ex-PM told Sky News: "This is a load of complete nonsense - absolute nonsense.
"Let me just tell you, Richard Sharp is a good and wise man but he knows absolutely nothing about my personal finances - I can tell you that for 100% ding dang sure.
"This is just another example of the BBC disappearing up its own fundament."
Mr Sharp this morning branded discussions around Mr Johnson's loan as a "distraction".
He said: "Our work at the BBC is rooted in trust. Although the appointment of the BBC chairman is solely a matter for the Government … I want to ensure that all the appropriate guidelines have been followed within the BBC since I have joined.
"The nominations committee of the BBC board has responsibility for regularly reviewing board members' conflicts of interest."
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Meanwhile, battling to get a grip on the double whammy claims, Mr Sunak today asked his ethics chief to begin an inquiry into Mr Zahawi.
The PM said: "Integrity and accountability is really important to me and clearly in this case there are questions that need answering.
"That's why I've asked our independent adviser to get to the bottom of everything, to investigate the matter fully and establish all the facts and provide advice to me on Nadhim Zahawi's compliance with the ministerial code.
"I'm pleased that Nadhim Zahawi has agreed with that approach and has agreed to fully co-operate with that investigation."
After months of scrutiny, in early January Mr Zahawi agreed to pay millions of pounds to the Treasury settle his tax affairs.
While Chancellor, he reached a settlement with staff at HMRC - the department he headed up - to pay up £4.8million of tax owed, including a 30 per cent penalty.
Mr Zahawi insisted the late payment on his earnings was “careless and not deliberate error”.
Mr Zahawi, a father of three who has amassed a personal fortune of up to £100million, has faced months of pressure over profits from the sale of YouGov, the polling firm he founded.
He has faced questions over whether he avoided tax by using an offshore company to hold shares in YouGov. A family trust, Gibraltar-registered Balshore Investments, held a stake worth over £20million but sold up by 2018.
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Mr Zahawi has said he was not a beneficiary of the trust, but records show money he owed to YouGov was partly repaid from Balshore dividends.
In a statement this morning the ex-Treasurer said: “I am confident I acted properly throughout."