The names of the defendants in the case of disgraced rock star Ian Watkins were mistakenly included on the court service's listing site, it has confirmed.
The development came as Peaches Geldof continued to be at the centre of a row for tweeting the names of the two mothers whose babies were involved in abuse by the singer.
The daughter of Boomtown Rats singer Bob Geldof posted a series of tweets explaining that she had assumed the names were already "public knowledge".
An HM Courts & Tribunals Service spokesman said: "We apologise that the names of the defendants in this case were mistakenly included on our court listing site. The names were quickly removed from the site, and action has been taken to ensure this does not happen again."
Detectives confirmed that they were investigating reports of what Peaches Geldof had done and were in talks with prosecutors.
She explained that she had deleted her tweets "and apologise for any offence caused as at the time of tweeting had only seen everyone tweeting the names at me so had assumed as they were also up on news websites and the crown courts public file that they had been released for public knowledge".
She added: "Will check my facts before tweeting next time. Apologies and lesson learned."
The celebrity posted the names of the two women on Twitter after reportedly reading them on a US-based website.
Lostprophets singer Watkins was branded a ''determined and committed paedophile'' after he pleaded guilty to a string of sex offences, including the attempted rape of a baby.
The 36-year-old, from Pontypridd, South Wales, plotted the abuse with the two mothers in a series of text and internet messages.
Peaches gives a full account of how she came to tweet the names of the two mothers involved.
"For all of those out there tweeting me about naming the paedophile mothers involved in the Ian Watkins case, the names have been in the public domain since December 12th when the court named them and put them up on their website for all to see," she begins by explaining.
"Half of Twitter had tweeted out the names also aside from my (now deleted) tweet.
"The babies will most probably be given new identities to protect them from future abuse from other paedos who know who they are / their names from the videos Watkins uploaded to paedo websites.
"The question of whether or not to give anonymity to criminals in cases like this will go on forever. However these women and Watkins will be getting three meals a day, a double bed, cable TV etc all funded by the tax payer alongside not being named apparently. It makes me sad."
She then moves on to explain that she had deleted her postings and apologises "for any offence caused".
Police yesterday underlined the seriousness of the situation.
Senior investigating officer Detective Chief Inspector Peter Doyle, of South Wales Police, said: "We are aware that the names of Ian Watkins' co-defendants have been published on social media channels.
"Clearly, there is strong public feeling about this case and many people are using social media forums to talk about the issues involved.
"We are currently in consultation with the Crown Prosecution Service regarding the matter and will take action if appropriate.
"Our primary objective as an organisation remains the safeguarding of vulnerable people and children.
"Victims of sexual abuse have a right to anonymity in order to protect their future welfare and we urge those discussing the issues raised online to be careful about using information that identifies victims in cases like this."
The seriousness of the situation has been reinforced by the Attorney General's office, which has warned that sex offence victims have automatic lifetime anonymity and publishing details that can lead to their identification is a criminal offence.
A spokeswoman for the Attorney General's office went on to explain that it was aware of the online posting and the fact that it had been deleted.
She said: "Victims of sexual offences have automatic lifetime anonymity and the publication of names or information which can lead to their being identified is a criminal offence. This is a police matter."
Peaches, 24, has more than 160,000 followers on Twitter, and has worked as a journalist, writing columns for the Daily Telegraph and Elle Girl and articles for the Guardian.
Watkins had previously "furiously" denied the charges but h is last-minute change of plea came ahead of what was scheduled to be a four-week trial at Cardiff Crown Court.
The charges included sexually touching a one-year-old and encouraging a groupie to abuse her own child during a webcam chat.
Watkins also admitted possessing and making child porn as well as launching the plot to rape a baby.
He will be sentenced with the two unnamed women at Cardiff Crown Court on December 18.