Peaches Geldof has apologised for tweeting the names of paedophile Ian Watkins' co-defendants to her 165,000 Twitter followers, as police confirmed they were investigating.
The two women found guilty alongside the ex-Lostprophets frontman have their identities protected so that their children, victims of sex abuse, may also have their identities kept secret. Both women also face jail.
Geldof posted the names of two women involved in the case on Twitter after reportedly reading them on a US-based website - but has since removed them.
Both the Attorney General and South Wales Police had previously warned people not to name the pair on social media.
In a series of tweets, Geldof wrote she believed the names were already in the public domain.
"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 Watjins uploaded to Paedo websites," she said.
"The question of wether [sic] or not to give anonymity to criminals in cases like this will go on forever. However these women and Watkins will be gettings 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. I deleted my tweets however 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. Will check my facts before tweeting next time. apologies and lesson learned.
Earlier she had tweeted: "‘The papers MUST name “woman A & B” who offered up their babies to this monster."
Watkins pleaded pleaded guilty to a series of "depraved" child sex offences including admitting to two charges of attempting to rape a baby.
Detective Chief Inspector Peter Doyle, of South Wales Police, told the Daily Mail: "We are currently in consultation with the Crown Prosecution Service regarding the matter and will take action if appropriate."