Britain's richest man, Sir Jim Ratcliffe, has said it would be "dumb money" to buy Manchester United -- the team he supported as a boy -- after claiming that the club have "lost the plot" since Sir Alex Ferguson retired as manager in 2013.

Ratcliffe, who is worth a reported £20 billion following the success of Ineos, his multi-national chemicals company, bought Ligue 1 club Nice for €110m in August after exploring moves for Chelsea, Newcastle and Leeds United.

But speaking to The Times, Ratcliffe said he did not consider United because "[Ineos] never wants to be the dumb money in town, never, never."

"Not at the moment, no," Ratcliffe said, when asked about buying United. "They are in quite a big pickle as a business.

"They haven't got the manager selection right, haven't bought well. They have been the dumb money, which you see with players like Fred.

"We won't look elsewhere until we have had a good run here [at Nice]. We need to find out how to be successful before you ever want to write a big cheque. It's quite difficult.

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"United have spent an immense amount since Ferguson left and been poor, to put it mildly. Shockingly poor, to be honest.

"We have a different approach here to be moderately intelligent about it. Try to do it more grass roots, trying to locate young talent.

"Some clubs seem to have an ability to do that, Southampton, Lille. United have done it really poorly. They have lost the plot there somehow."

Ratcliffe toured Chelsea's Cobham training ground while considering a move to buy the Roman Abramovich-owned club, but he said the valuations of Premier League clubs was another barrier to buying an English team.

"You quickly get into some pretty stratospheric numbers," he added. "And even though clubs have those valuations today, nobody has ever paid those amounts of money.

"How much did Abramovich pay for Chelsea, £100m? The Glazers [at United], what £500m? You can say it's worth three, four billion but no one has ever paid those sums.

"Ineos has always tried to take a sensible approach. We don't like squandering money or we wouldn't be where we are today. It's part of our DNA, trying to spend sensibly."