Former Cabinet minister Sajid Javid has said he made a “mistake” backing Liz Truss for Tory leader, as he accused the ex-PM of failing to show respect for “our key economic institutions”.

The former chancellor and health secretary, who backed Ms Truss in the first Tory leadership contest of the year, said her choices on tax cuts and spending were “ultimately where she failed”, as she went “too far”.

He added that he still considers Boris Johnson a “friend”, despite resigning from his cabinet in July, but he can understand why the ex-PM “might take a different point of view”.

Asked if he misjudged Ms Truss’s character, Mr Javid told LBC’s Tonight With Andrew Marr that he made a “mistake” backing her.

“In hindsight, I made a mistake. I think many of us did,” he said.

“I wanted her to do well, of course I did. I wanted her to deliver on the things that she said she would, but… she went a lot further when it came to tax cuts, she went even a lot, lot further when it came to spending, and she didn’t show respect for our key economic institutions.

“And that is ultimately where she failed.”

He said her premiership was “not what I would have expected”, and that is “probably the view of most of my colleagues”.

“But you know, I readily admit, in hindsight, of course it was a mistake, and she went too far. And she’s admitted that herself, and she was right to resign,” he added.

Mr Javid said Rishi Sunak is the “best possible Prime Minister this country could have right now”, and he is “very confident” about how he will approach the challenges facing Britain.

He also said politics is “tough” in terms of personal relationships, as he reflected on his divorce with Mr Johnson’s cabinet.

“In terms of personal relationships, it is tough,” he said.

“I still think of Boris Johnson as a friend. But after leaving my job as health secretary, and I set out my reasons, you can understand why… (he) might take a different point of view.

“But it’s not personal. These are all decisions based on one’s values, based on one’s principles. And you’ve got to do what is right, ultimately.”