Detectives investigating child sexual exploitation in Rotherham have made multiple arrests in Leeds.
Detectives have arrested 40 people from across the country over the past two months.
The 38 men and two women were questioned following allegations made by 13 victims about sexual abuse against them between 1997 and 2015, the National Crime Agency (NCA) said.
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The arrests are part of the ongoing Operation Stovewood investigation.
An NCA spokeswoman said the people arrested are aged between 29 and 53 and are from Sheffield, Rotherham, Leeds, Dewsbury, and Maidstone in Kent.
All have been bailed or released under investigation pending further inquiries.
The spokeswoman said the victims were aged between 11 and 26 at the time of the alleged offences.
Carl Vessey-Baitson, from the NCA, said: "Arresting such a large number of individuals, as part of one Stovewood sub-operation, shows our desire to listen to victims and bring offenders to justice is not wavering.
"Stovewood is a challenging and complex investigation, with victims and survivors reliving abuse that took place many years ago.
"To date we have engaged with over 410 victims and survivors and have arrested or interviewed by appointment 94 suspects, meaning this is the largest law enforcement investigation into non-familial CSAE (child sexual abuse and exploitation) ever undertaken in the UK.
"Conducting such an investigation can only be achieved with the support and co-ordination of our partners, and South Yorkshire Police and Rotherham Metropolitan Borough Council continue to provide invaluable assistance."
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The NCA launched Operation Stovewood, at the invitation of South Yorkshire Police, after Professor Alexis Jay's 2014 report into the rape, grooming and trafficking of hundreds of children in Rotherham.
The Jay Report described how more than 1,400 children had been affected - a figure which was later established to be an underestimate by Operation Stovewood, which has identified 1,523 victims.
Towards the end of 2018, the NCA said it had 151 designated suspects, 275 other people under investigation and 296 female survivors of exploitation actively engaging with officers.
The NCA has full control of allegations between 1997 and 2013, with 250 staff and an annual budget that will soon reach £15 million a year.
It is estimated the operation will cost more than £90 million by 2024 - the date to which current planning extends.