MANCHESTER United fans last night pledged to stage mass demonstrations outside this month's FA Cup Final in protest at US sports tycoon Malcolm Glazer's £790m purchase of the club.

Mr Glazer effectively completed his controversial buyout yesterday by capturing the 28.9 per cent stake owned by Irish racing tycoons John Magnier and JP McManus.

The multi-millionaire, who has been trying to buy England's biggest football club since February last year, also secured the shares of Scottish mining entrepreneur Harry Dobson to take his stake in United to 62 per cent - within touching distance of the 75 per cent needed to take the company off the Stock Exchange into private hands.

Mr Glazer will bid for the remainder of the shares this morning - offering 300p per share - and, while supporters' groups have promised to fight the takeover, the 76-year-old can force a compulsory purchase once he reaches a 90.01 per cent threshold.

Supporters opposed to Mr Glazer's plans held a demonstration outside Old Trafford last night -with more protests likely outside Cardiff's Millennium Stadium on May 21.

"It's the news that all Manchester United supporters were dreading to hear," said John Burgess, secretary of the North-East branch of the Manchester United Supporters Club which, combined with the Cleveland branch, has more than 800 members.

"I personally own about 2,500 shares and I can't afford to write off that amount of money. I'd love to, because I want to hold onto what I own. But I can't and it will be a sad day when I have to sign them over to Glazer.

"We called off one demonstration because he was given a deadline and we wanted to see what happened. But this changes everything and the gloves are off. We want to put our views across and, because of the timing of all of this, the FA Cup Final looks like being our only chance of doing that.

"I think you're going to see a major demonstration at Cardiff. The eyes of the world are on the FA Cup Final, and we want those eyes to see what a disgraceful situation this is."

Mr Burgess' views were echoed by Oliver Houston, of Shareholders United, a group of private shareholders. He said fans may stay away in protest next season.

He said: "Our message to Malcolm Glazer and to people daft enough to lend him all this money is that not only will you not be able to increase your profits, but you are going to see a very sharp fall in profits.

"Manchester United is going to become an extremely tainted brand. People will feel that this is no longer their club."

Former manager Tommy Docherty said: "The man has almost bought the club and he knows nothing about football. Manchester United's heart and soul has been sold."

The current United board said it would wait for the formal terms of the offer before deciding on its response. It has rejected Mr Glazer's bids in the past as it would saddle the club with too much debt.

Mr Glazer - who also owns American Football side Tampa Bay Buccaneers - is understood to have trimmed the amount of borrowing needed, but still needs a massive increase on United's £12.4m half-year profits to make his move viable.

That could force him to challenge the collective bargaining agreement of the existing Premier League TV contract in an attempt to sell Manchester United's games as a separate package.

Mr Glazer has promised United manager Sir Alex Ferguson a £25m summer transfer kitty, although the Scot has previously spoken out against any change to the club's Stock Market position.

Sir Alex may now consider his own position, but Mr Glazer will be loath to lose the most successful manager in the club's history.