Ratcliffe's INEOS bidding to buy Man Utd

Jim Ratcliffe's chemical company INEOS has formally entered the bidding process to buy Premier League soccer club Manchester United.

The Glazer family, United's US owners, said in November they had begun looking at options for the 20-times English champions, including new investment or a potential sale, 17 years after they bought the Old Trafford club.

In August, British billionaire Ratcliffe, one of Britain's richest men and a boyood fan of the club, expressed interest in buying United.

"I can confirm that we have formally put ourselves into the process," an INEOS spokesperson said in a statement on Tuesday.

The Times newspaper, which first reported the news, said formal bids were expected to start next month, with United potentially changing hands by the end of the season.

Interest from the United States, the Middle East and Asia is also expected.

Manchester United's shares rose 1.2 per cent in New York trading on Tuesday afternoon.

INEOS has long been involved in sport, with the company acting as principal partners to eight-times Formula One champions Mercedes, owning the INEOS Grenadiers cycling team and serving as performance partner to the New Zealand rugby team.

The energy company's interest in the United sale process comes after the group also bought French Ligue 1 club Nice in 2019.

Ratcliffe's name was widely mentioned among United fans as someone many would welcome, although there are fears he might be priced out with some estimates putting the club's worth at more than $US4.5 billion ($A6.4 billion).

Last year, he failed in an attempt to buy London club Chelsea, which was purchased by an investment group led by American Todd Boehly and Clearlake Capital.

United fans have been clamouring for a change of ownership and the Glazers, who also own the National Football League's Tampa Bay Buccaneers, have been the target of intense criticism as the team last won silverware back in 2017.

United's net debt, another bone of contention among fans, had grown by nearly 23 per cent to 515 million pounds ($A905 million) by September.

The club are currently fourth in the league standings on 38 points after 18 games, one point behind their local rivals Manchester City but nine adrift of leaders Arsenal.