Treasury was aware of investigation into Nadhim Zahawi’s finances, sources claim

Rishi Sunak has appointed an ethics adviser to look into Nadhim Zahawi’s dealings with HMRC. Photograph: Tim Hammond/No10 Downing Street

The matter of who knew what about Nadhim Zahawi’s dealings with the taxman and when in Whitehall and No 10 is the subject of intense scrutiny and could yet define Rishi Sunak’s premiership.

Sunak has sought to put down suggestions he was aware that Zahawi paid a penalty to HMRC prior to his appointment as the Conservative party’s chair on 25 October 2022.