Malcolm Glazer owns the Tampa Bay Buccaneers

Mr Glazer said he had bought a further 2.41 million shares, taking his holding to 50.27 million shares or 19.2% of the English Premiership club.

The move is likely to renew speculation of a possible takeover bid for the world's richest football club.

Mr Glazer, who owns American football's Tampa Bay Buccaneers, has said he has no plans to mount a bid for United.

Latest move

But the club, which finished third in the premier league last season, has been the subject of persistent takeover rumours.

MAN UTD'S FINANCIAL STRENGTH Stock market value approx £675m Profits of £27m in Aug 03-Jan 04 Turnover of £92m in Aug 03-Jan 04 Check out Man Utd's share price

Manchester United's two biggest shareholders, Irish race horse owners John Magnier and JP McManus, hold 28.9% of shares in the club through their company Cubic Expression.

Mr Glazer last raised his stake in the club in April, buying up a further 4.1 million Manchester United shares.

He can continue to buy shares - without making a formal takeover announcement - until he owns 30% or more of Manchester United's stock.

However, many fans have expressed concern over the possibility of an outright takeover by one of the main shareholders in the club.