Rape Crisis Scotland says the leak of confidential documents relating to the David Goodwillie civil case is “a clear breach of the justice process”.
We revealed on Monday that police were aware of the matter and “gathering more information”.
The private correspondence emerged on social media and was shared by supporters of the shamed footballer.
It came just days after Goodwillie gave his first interview about the 2017 hearing that saw a judge rule the then-Dundee United striker and former teammate David Robertson raped Denise Clair six years earlier.
‘Robust action’
The sexual assault charity told The Courier: “We are extremely concerned by the completely unacceptable and unlawful leaking of confidential, and irrelevant, information from a civil rape case.
“This is a clear breach of the justice process and we expect appropriate and robust action to be taken.”
The Law Society of Scotland says the police probe means it is unable to comment.
Meanwhile, one top defence lawyer has called the leak “an appalling invasion into someone’s privacy”.
Another solicitor told us: “Not only is their release a gross invasion of privacy but it is also potentially a contempt of court.
“Anyone re-sharing these materials should think very carefully about the potential consequences of doing so.”
Goodwillie, 34, has mounted a PR campaign this month, vowing to tell “his truth” about the events of 2011.
Last week, following a series of tweets about the case, the former United and Raith Rovers forward gave an hour-long interview to podcaster James English.
On Saturday, Glasgow United were warned by council leader Susan Aitken that the club could be evicted from its home ground if it signs the ex-Scotland player.
David Goodwillie ruled rapist
Lord Armstrong heard from 20 witnesses during the civil case, which hinged on whether Ms Clair was too drunk to give consent to have sex with the players.
Goodwillie and Robertson said it was consensual.
Witnesses testified to Ms Clair being extremely drunk when she left a club in a taxi with the pair.
Medical and forensic witnesses backed her story and Lord Armstrong ruled Ms Clair had been raped, awarding her around £100,000 in damages.
Ms Clair later revealed lawyers for the footballers – who haven’t paid a penny out of the court-ordered compensation – had offered her up to £115,000 to drop the case.
The duo also lost an appeal against the civil ruling in November 2017.
Goodwillie – arrested and charged with rape six years earlier before the Crown Office dropped the charges and said there was insufficient evidence to bring the case to court – was declared bankrupt 17 months later.
Robertson, who was never charged, quit football after the civil court ruling.