British billionaire and Manchester United co-owner Jim Ratcliffe wants to build a new stadium for the club as he aims to bring back its glory days in the Premier League and European competitions, he told the BBC on Wednesday.

Ratcliffe's $1.25 billion deal for a 25% stake in the club, in which he will also invest $300 million into infrastructure and take charge of their soccer operations, was completed on Tuesday.

United have played at their current Old Trafford stadium, which has a capacity of 74,310, since 1910.

"There is a quite a big argument, in my view, for regenerating that whole south side of Manchester... the nucleus of it being a new stadium," he said.

"(It) would be a world class state of the art stadium, which could take England games it could take the FA Cup final, it could take the Champions League final, and it could service the north of England."

The INEOS chairman, who grew up a United fan, said the only reason he got involved in the club was to see it "restored to where it should be in football".

"I think it's the biggest club. It's the most well known club in the world. It has the greatest history in the world. And it should be playing the greatest football in the world, which it has been from time to time," he said.

United last won the Premier League in 2012-13, which was Alex Ferguson's final season as manager.

Ratcliffe said bringing true change in the club's environment would take at least two to three seasons.

"Nobody has been successful in that Manchester United environment for the last 11 years. So that would say to me that there's something wrong with the environment," he said.

"It's not constructive for me to blame anybody. It's just a fact of life."

Ratcliffe said United would need "to walk to the right solutions, not run to the wrong."

But echoing a famous phrase from Ferguson, he wants eventually to get the better of rivals Manchester City and Liverpool.

"I'd want to knock them all off their perch," he said.

"We're friends in the sense that we're all in the North West, but they are the enemies. They're clearly our biggest rivals and competitors in the UK. And then obviously you've got two or three clubs in Europe. That's what we're there for. Knocking them off their perch."

The 71-year-old said his trusting relationship with Joel and Avram Glazer would be key to his partnership with the Glazer family, which holds the majority stake at United.

"What I'd like to say to the fans is, you know, give us a little bit of time, try to be patient and we'll try to build Manchester United back to where it should be, which is one of the very elite clubs in Europe," he said.

United are sixth in the league and host Fulham on Saturday.