RISHI Sunak was asked if the job of Prime Minister was ‘too big for him’ as he came under pressure over the tax affairs of Tory party chair Nadhim Zahawi.

He said the probe by ethics adviser Sir Laurie Magnus should be allowed to run its course and described calls for the cabinet minister to step aside as “opportunism.”

Questions are being over a seven-figure sum - including a substantial penalty - paid to HMRC by Mr Zahawi when he was Chancellor. 

In a statement on Saturday, he claimed he had made a “careless” and not a deliberate mistake. 

He has so far refused to resign. Yesterday, No 10 ordered Sir Laurie to investigate whether or no Mr Zahawi had broken the ministerial code.

READ MORE: Investigation ordered into Nadhim Zahawi's tax dealings as chancellor

The plight of the Tory chairman was raised by both Labour leader Sir Keir Starmer and the SNP Westminster group leader Stephen Flynn. 

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The Aberdeen South MP quoted Robert Burns as he described the Tory leader and his colleagues as a “parcel of rogues.”

He said this was “now a matter of the Prime Minister's own integrity and accountability.” 

Mr Sunak insisted he was “standing up” for “proper due process.” 

Notably, the Prime Minister did not defend Mr Zahawi. He also conceded that when he spoke in the chamber last week, he did not know the full details of his minister’s tax arrangement.  

READ MORE: Nadhim Zahawi’s tax affairs: A timeline of how the controversy played out

Sir Keir asked Mr Sunak if he agreed that any politician seeking to avoid the taxes they owe was “not fit to be in charge of taxpayers’ money.”

The Tory leader said he was “pleased to make my position on this matter completely clear.” 

He said: “The issues in question occurred before I was Prime Minister.

"With regard to the appointment of the minister without portfolio, the usual appointments process was followed. No issues were raised with me when he was appointed to his current role. 

“And since I commented on this matter last week, more information has come forward and that is why I have asked the independent adviser to look into the matter. 

“Now, I obviously can't prejudge the outcome of that, but it is right that we fully investigate this matter and establish all the facts.”

The Labour leader said the failure to sack Mr Zahawi showed how “weak as a Prime Minister” Mr Sunak is. He was “overseeing chaos” and “overwhelmed at every turn”.

“Is he starting to wonder if this job is just too big for him?” he asked.

Mr Sunak said the difference between him and the Labour politician was that he stood “by my values and my principles even when it is difficult.” 

“When I disagreed fundamentally with the previous Prime Minister, I resigned from the government. For four long years, he sat next to [Jeremy Corbyn]. 

“When anti semitism ran rife, when his predecessor sided with our opponents. That's what's weak. He has no principles and just petty politics.”

Speaking after Prime Minister's Questions, Mr Sunak's press secretary refused to say if the Tory leader has ever paid a tax penalty.

“You wouldn’t expect me to get into the Prime Minister’s tax affairs, they are confidential," they said.

“The tax affairs of an individual, irrespective of who they are, are confidential.”