The group, which holds a 1.4 per cent stake in the club, has listed the mobile phone numbers of senior Smithfield staff, including CEO John Antcliffe and director John Kiely on its website, encouraging fans to 'let them know how you feel about our friend Malcolm Glazer'.
Antcliffe has taken security advice after fans sent emails to the firm, which is working for Glazer's acquisition vehicle Red Football. 'The vast majority have been measured in their tone,' Antcliffe told PRWeek. 'But one or two have not been so friendly.'
Shareholders United chair Nick Towle said he was in talks with three PR firms to help it continue its campaign despite Glazer's acquisition of the club.
Shareholders United has also listed contact details for Smithfield clients Scottish & Newcastle (S&N), BHP Billiton and Stagecoach.
S&N and Stagecoach said they would not review their relationship with Smithfield, as urged by Shareholders United. BHP Billiton declined to comment.