Manchester United is suing a protester after claiming that details of 400 corporate clients of the club were leaked online to foment action against its American owners.
The Premier League leaders say in a writ filed against Thomas McKenna at London's High Court that his actions led to some business premises and homes being attacked.
Campaigns have been intensified against Malcolm Glazer and his family in a bid to force them to sell United, which has debts that currently exceed 500 million pounds ($809 million). United had no debt when it was bought by the Glazer family in 2005.
"The defendant's express purpose in publishing the list was ... to embarrass and exert pressure and to incite others to exert pressure upon the clients," the writ said.
United said Thursday it does not know how the data was stolen from the club which was later posted on a website used by supporters opposing the Glazers. The site is no longer online.
"The theft of data led to some of the companies named on the list having their property attacked and suffering significant personal distress," the club said in a statement. "The club has a duty to demonstrate to all our fans that we will not tolerate that and will take action against the perpetrators. We take data security very seriously. Doing nothing was not an option."
United is pursuing financial damages and wants the information destroyed. McKenna has never been a member of the club or owned a season ticket at Old Trafford.
McKenna could not be reached for comment.
Manchester police said that last August "a 43-year-old man from Tameside was arrested on suspicion of an offense under the computer misuse act. No further action was taken as no criminal offenses were found to have taken place."