LONDON, United Kingdom (AFP) — Jim Ratcliffe has directly contacted Manchester United fans to plead for patience after agreeing to take a stake in the struggling English football giants.

United announced on Christmas eve that British billionaire Ratcliffe had agreed a deal to buy a 25 percent stake in the club for about $1.3 billion, with Ratcliffe vowing to return the Premier League side to the "top of world football."

United also announced in a statement that Ratcliffe's INEOS Chemicals company would take control of football operations after years of under-achievement under the United States-based Glazer family, the club's current owners who retain majority control at Old Trafford.

INEOS director of sport Dave Brailsford, best known for his work in cycling, was in the crowd at Old Trafford on Tuesday as United came from 2-0 down to defeat high-flying Aston Villa as they moved up to sixth in the Premier League.

Ratcliffe, 71, has now written to several fans' groups, including the Manchester United Supporters' Trust, insisting INEOS "are in for the long-term" but stressing on-field success "will require time and patience" with fans also hoping he can redevelop a crumbling Old Trafford ground.

"I wanted to write to you at this time given the critical role of the fans to the future of Manchester United as we recognise our responsibility as custodians of the club on your behalf," Ratcliffe said.

"I believe we can bring sporting success on the pitch to complement the undoubted commercial success that the club has enjoyed."

"It will require time and patience alongside rigor and the highest level of professional management."

"You are ambitious for Manchester United and so are we. There are no guarantees in sport, and change can inevitably take time but we are in it for the long term and together we want to help take Manchester United back to where the club belongs, at the very top of English, European and world football."

"I take that responsibility very seriously."