Brown seeks to gag fans' group

Whistle also claimed that West Ham's board have resisted approaches from "serious parties" for a much-needed cash injection. Again the club refute this allegation, with Herbert Smith saying: "There have been no serious offers of fresh investment."

Whistle are concerned that West Ham's precarious financial position will force more player sales in the summer - even if they are promoted to the Premiership. Not true, say the club's lawyers, who claim "such an allegation is defamatory and highly damaging".

The club are also upset that a number of Whistle's questions "imply misconduct" on the part of West Ham by raising issues about preferential corporate hospitality and links with freemasonry.

Whistle, who claim to know of City investors prepared to pump £20m into the club, are understood to be determined to continue with their campaign to oust Brown regardless of the legal action.

The group's aim is to seize control of the club and appoint a new management structure.

But their attempts have floundered as the existing directors retain the support of the club's major shareholders, the Warner and Cearns families.

Whistle's dossier, delivered to the club last week, was designed to cause maximum embarrassment.

Brown has since attacked the timing of the campaign, which coincides with West Ham's play-off bid. Alan Pardew's side must avoid losing by four goals at Wigan on Sunday to guarantee a top-six finish.