Rishi Sunak made “the right decision” by sacking Nadhim Zahawi, the chairman of the Scottish Conservative Party has said.

Craig Hoy told the BBC’s Sunday Show: “It was only right and proper that he asked Sir Laurie Magnus, his ethics adviser, to look into this issue, and so Laurie has come back and swiftly concluded that Nadhim has broken the Ministerial Code and the Prime Minister has then acted decisively in removing Mr Zahawi from office.

“I think the Prime Minister has done the right thing really.”

Mr Zahawi was dismissed as Conservative Party chairman by Mr Sunak on Sunday morning after an ethics inquiry into the handling of his tax affairs found a “serious breach” of the Ministerial Code.

The investigation was ordered following reports that the former chancellor had paid a penalty as part of an estimated £4.8 million settlement dispute with HM Revenue & Customs.

Pressed on why it took so long to dismiss Mr Zahawi, Mr Hoy defended the Prime Minister, saying the sacking “hasn’t been hanging around for months” and that Mr Sunak acted “decisively”.

He also said the Prime Minister had insisted he was not aware of “those tax issues and his tax affairs” when he appointed Mr Zahawi to Government.

Asked about Suella Braverman, who was briefly sacked for “a technical breach” of the Ministerial Code before being reappointed, and if that was going to happen in Mr Zahawi’s case, Mr Hoy replied: “I think the Home Secretary had a minor breach of the Ministerial Code.”

He insisted Mr Sunak had shown “integrity” by being decisive.

But other parties in Scotland questioned the Prime Minister’s approach to the dismissal, with the SNP saying Mr Zahawi should have been sacked earlier, and that Mr Sunak’s “dithering and indecision” had kept him in post.

Spokeswoman Kirsty Blackman said: “Nadhim Zahawi should have been sacked well before now, but it has only been Rishi Sunak’s dithering and indecision that has kept him in post.

“The Prime Minister shouldn’t have needed an ethics adviser to tell him that a sitting chancellor should not be in a tax dispute about millions of pounds of unpaid taxes.

“Sunak still has questions to answer over this whole affair, about what he knew about the settlement and what advice he received about Zahawi’s tax on his appointment.”

The Scottish Greens said Mr Zahawi’s dismissal “raises big questions” over the Prime Minister’s judgment.

The party’s economy spokeswoman, Maggie Chapman, said: “It is good that Zahawi has gone, but this isn’t just about him.

“It’s also about the judgment of the Prime Minister, who clearly has serious questions to answer over this whole affair.

“What did he know, when did he know it, and why has he dithered so long when it was clear Nadhim Zahawi had broken the Ministerial Code and the trust placed in him?”