Years of Tory strife have caused Britain to become "the sick man of Europe," said Guy Hands, one of the party's leading backers and chairman and chief investment officer of private equity firm Terra Firma.

The Conservative Party is not fit to run the country, he said. "I think its got to move on from fighting its own internal wars and focus on what needs to be done on the economy and admitting some of the mistakes they’ve made in the last six years which have frankly put this country on a path to be the sick man of Europe," Mr. Hands said.

Brexit was the catalyst for many problems, he said. "The reality is when they did Brexit, they had a dream. And the dream was a low-tax, low-benefit economy," he said on the BBC Today program.

He said outgoing Prime Minister Liz Truss tried to push the policy through, but it didn't work. "Once you accept that you can't actually do that, then the Brexit that was done is completely hopeless, and will only drive Britain into a disastrous economic state," Mr Hands said.

"So I think [if] the Tory party can own up to the mistake they made and how they negotiated Brexit and have somebody leading who actually has the intellectual capability and the authority to renegotiate Brexit, there is a possibility of turning around the economy, but without that the economy is frankly doomed."