Detectives from the FBI and the Scotland Yard yesterday arrested 90 children and two preachers in a raid on a suspected terror cell in Mombasa.
The al Madrasatul Falan in Likoni, which had been registered as a madrasa and a rehabilitation center, was also shut down.
The children, some as young as five, were of various nationalities, including the US, UK, Canada, South Africa, Saudia Arabia, Somalia, Zambia, Uganda and Kenya.
Police say they were being indoctrinated on terrorism activities. They were interrogated at the Coast regional police headquarters in Mombasa.
They were asked about the nationality of their parents, details of any physical abuse while at the madrasa and whether they were sexually harassed.
The FBI said they suspected body harm was inflicted on the children
The arrested preachers were handed over to the Anti-Terrorism Unit and Directorate of Criminal Investigation officers.
A senior officer involved in the operation told the Star the UK was interested in one captive said to be a Syria returnee from Britain.
He was traced to the madrasa. Detectives said the 20-year-old has valid travel documents and was sent to the center by his parents. He is alleged to be an IS member.
"He was sent to the country as part of IS punishment,” the officer said.
It has emerged the UK contacted Interpol and the DCI to trace him.
The Madrasa has both boarding and day scholars and hosts several children, including refugees from war-torn Somalia.
The UK is grappling with home grown terror, although most suspects are said to be refugees from Iraq and Syria. The refugees were instrumental in the two London Subway attacks in September.
Foreign children arrested during the raid will be repatriated, an officer handling the case told the Star.
"Kenyans will be handed back to their parents after intensive interrogation over any torture and indoctrination," he said.
Grace Ndirangu, officer in charge of Anti-Human Trafficking and Child Protection Unit at the Coast DCIO, said they raided the cell following cases of children mistreatment.
"We received two cases of child abuse from parents and decided to conduct an operation. They will be interrogated and profiled before being being released to their families," Ndirangu said.
Some parents condemned the raid.