Former singer Ian Watkins has been attacked in prison while serving a 29-year sentence for child sex offences.
The Mirror newspaper reports that the disgraced rock star, who is being held in HMP Wakefield, was stabbed.
A Prison Service spokesperson said police were investigating an incident that took place at the prison on Saturday.
They added: "We are unable to comment further while the police investigate".
Watkins was jailed in december 2013 for a string of child sex offences, including the attempted rape of a baby.
While not wanting to comment specifically about the attack on Watkins, Prison Officers' Association vice-chair Dave Todd said he was concerned for staff and prisoners over the rising number of incidents they are being exposed to in jails.
Watkins was sentenced to 29 years in prison with a further six years on licence, but he will be eligible for parole after serving two thirds of the prison term.
His two co-defendants, the mothers of children he abused, were jailed for 14 and 17 years.
During sentencing, Mr Justice Royce said the case broke "new ground" and "plunged into new depths of depravity".
Watkins admitted the attempted rape and sexual assault of a child under 13 but pleaded not guilty to rape.
Judges rejected an appeal by Watkins in 2014 to reduce the length of his jail term
As a rock star in his 20s, he sold millions of albums around the world and commanded huge arena crowds.
Formed in 1997, Welsh rock band released five studio albums in total, including a number one album in the UK and two Top 10 singles. They also saw some success in the US, where their second and third albums both reached the Top 40.