A mass anti-Glazer protest took place at Old Trafford ahead of Sunday afternoon's Barclays Premier League meeting between Manchester United and Stoke.
With feelings running high on the final day of the season, hundreds of supporters congregated outside the directors' box and chanted venomous anti-Glazer songs before being moved on by police.
There were unconfirmed reports of at least one smoke bomb being let off inside the Megastore at the front of the stadium, and at least one injury being reported as a result.
Avram Glazer, the co-chairman of Manchester United, had been due to attend the game but never made the journey due to flying restrictions imposed because of the on-going ash cloud disruption.
The demonstration is the start of an escalation in the anti-Glazer campaign, aimed at driving the Americans out of Old Trafford.
A bid from the Red Knights group of wealthy United fans is expected in the next few weeks, although the consistent stance from the Glazer family has been that they are not interested in doing a deal.
The Glazers have never been welcomed by a minority of supporters, but those feelings have grown markedly this season as the full scale of the debts incurred in their controversial takeover have become clear.
A successful bond issue earlier this year highlighted the potential for the sale of both Old Trafford and the club's state-of-the-art Carrington training complex should the Glazers hit problems with the repayments.
Although he has backed the Glazer family, Sir Alex Ferguson has previously defended the supporters' right to protest, whilst chief executive David Gill admitted he would prefer to see fans wearing the club colours of red and white rather than the highly visual green and gold scarves now being worn by a vast majority of supporters.
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