Lostprophets formed in 1997 and have sold more than 3.5 million records worldwide.
An investigation is to be launched into whether South Wales Police acted quickly enough in arresting Lostprophets singer Ian Watkins on suspicion of child sex offences.
Watkins, 35, from Pontypridd, has been charged with conspiracy to rape a one-year-old as well as two incidents of conspiring to engage in sexual contact with two young children, and possessing, making and distributing indecent images of children.
The singer was arrested along with two women in December. The Independent Police Complaints Commission (IPCC) is investigating if South Wales Police acted "expediently" before arresting the 35-year-old.
IPCC Commissioner for Wales Tom Davies said: "We received a referral from South Wales Police on 25 January 2013 relating to Ian Watkins. Following a thorough assessment I have decided that we will carry out an independent investigation.
"Our investigation will determine whether or not South Wales Police failed to take appropriate and timely action in relation to information they were in receipt of in advance of Mr Watkins' subsequent arrest.
"We are aware of four forces having provided South Wales Police with information but, as criminal proceedings are active, it would be inappropriate to publish further information at this time."
Chief Sup Tim Jones, head of South Wales Police Professional Standards Department, said: "South Wales Police will fully support the Independent Police Complaints Commission's independent investigation and are committed to responding promptly to its findings."
Watkins will appear Cardiff Crown Court on 11 March.
One of his co-defendants, aged 24 and from Bedford, has been charged with the same offences as Watkins.
The second woman, a 20-year-old from Doncaster, is charged with five of the same offences but not conspiracy to rape.
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