The move comes as one of the club's most famous former managers Tommy Docherty, added his voice to the concerns being expressed by fans and MPs about the possible take-over.

The Chief Executive of the FA, Graham Kelly, said the club had a duty to talk to its own fans about any sale.

"There is a responsibility of those concerned with such deals to explain them to the wider football audience, not least their own supporters. We have to assess the implications very closely indeed."

Mr Kelly welcomed the announcement that the bid would be referred to the Office of Fair Trading.

His intervention followed confirmation by United that negotiations were underway with BSkyB, and the announcement of plans to extend the club's ground, Old Trafford, by 12,400 seats.

Murdoch 'not a football man'

Mr Docherty, who was the team manager from 1972 to 1977, said he realised a take-over by BSkyB could mean extra investment in the club.

However, he feared the company would not know how to run a football club properly.

"Rupert Murdoch has got mega money hasn't he. But he is not really a football man and that's the thing that what worries me," he said.

"I care about the supporters of this club and you have got to love this club and be involved in it to know what it is all about."

United fans also expressed similar concerns. Andy Walsh, from the Manchester United Independent Supporters Association, said he feared that if the bid was successful the club might move away from Old Trafford.

Another supporter was concerned about the wider implications for the game if satellite TV channels got a greater say in the sport by buying up clubs.