Child protection officers are to be investigated by the police complaints watchdog over delays in acting on intelligence about hundreds of suspected paedophiles.
The Independent Police Complaints Commission said it will investigate how staff at the Child Exploitation and Online Protection Centre (Ceop), which is now part of the National Crime Agency (NCA), dealt with information received by Canadian police in July 2012.
The NCA made a referral to the IPCC in September last year after it emerged Ceop had failed to contact police forces concerning the intelligence - provided by Toronto police under an operation called Project Spade - for over a year.
It emerged last year that the tip-offs included information about disgraced Cambridgeshire medic Myles Bradbury as well as teachers Martin Goldberg and Gareth Williams, who both secretly filmed children.
Williams, from Cardiff, is now serving a five-year jail term but Goldberg was found dead a day after police first contacted him.
IPCC commissioner Carl Gumsley said: " The public are rightly concerned about the safety of the most vulnerable members of society and issues concerning the protection of children.
"Independent IPCC investigators will be examining closely the actions taken by Ceop and NCA officers and staff over a 16-month period to determine if they acted appropriately and promptly as well as looking at any possible organisational failings."
Following the initial referral, the IPCC asked the NCA for more information, including whether any individual staff should be referred.
Last month, the NCA and Lincolnshire Police subsequently referred the actions of three officers, two NCA officers and one junior Lincolnshire officer who was on secondment with Ceop at the time.
Investigators in Toronto gave 2,345 pieces of intelligence linked to accessing child abuse images to Ceop, which included customer details of purchasers of indecent DVDs and videos.
But it was only in November 2013 that the information was finally passed on to police, when Ceop was taken into the newly-created NCA.
Among the tip-offs was paediatric doctor Myles Bradbury, who was later jailed for 22 years for abusing 18 sick boys in his care and possessing 16,000 indecent images.
Another man on the list, teacher Martin Goldberg, was found dead the day after police first called on him.
A subsequent search of his house was conducted and 7,257 indecent images of children that he had downloaded from the internet were found.
In addition, 1,468 images that appeared to have been created by Mr Goldberg were discovered, including 465 images depicting nudity that appeared to have been taken or recorded at Southend Leisure and Tennis Centre swimming pool changing rooms.
A further 75 depicting nudity that appeared to have been taken or recorded by Mr Goldberg at Thorpe Hall School boys' changing rooms were also found.
Cardiff deputy head Gareth Williams, 48, admitted 31 charges including nine of voyeurism and 20 of making indecent photos last May.