Shamima Begum, who fled the UK and joined the Islamic State group, was smuggled into Syria by an intelligence agent from Canada.
Files seen by the BBC show he claimed to have shared Begum’s passport details with Canada and smuggled other Britons to fight for IS.
Begum’s lawyers dispute the stripping of her citizenship, arguing that she was a victim of trafficking.
Canada and the UK declined to comment on security concerns.
Begum was 15 when she and two other schoolgirls from east London – Kadiza Sultana, 16, and Amira Abase, 15 – traveled to Syria to join the IS group in 2015.
At Istanbul’s main bus station, the girls met Mohammed Al Rasheed, who would facilitate their journey to IS-controlled Syria.
A senior intelligence officer from an agency that is part of the global coalition against ISIS confirmed to the BBC that Rasheed was providing information to Canadian intelligence services while smuggling people to ISIS.
The BBC has obtained a file on Rasheed which contains information collected by law enforcement and intelligence agencies, as well as material recovered from its hard drives, which provide extraordinary details about its operation.
He told authorities that he collected information about the people he helped in Syria because he passed it on to the Canadian Embassy in Jordan.
Rasheed, who was arrested in Turkey days after smuggling Begum into ISIS, told authorities he shared a photo of the passport the British schoolgirl was using.
The Metropolitan Police were looking for her, although by the time Canada received her passport details, Begum was already in Syria.
The file shows that Begum was transferred to Syria through a large network of IS smugglers controlled from the group’s de facto capital of Raqqa.
Rasheed was responsible for the Turkish side of this network and facilitated the travel of British men, women and children to IS for at least eight months before helping Begum and his two friends.
Begum told the BBC’s upcoming I’m Not A Monster podcast: “He organized the whole trip from Turkey to Syria… I don’t think anyone could have made it to Syria without the help of smugglers. .
“He had helped a lot of people get in… We did whatever he told us to do because he knew everything, we knew nothing.”
Rasheed kept information about the people he helped, often photographing their identity documents or secretly filming them on his phone.
A recording shows Begum and his friends getting out of a taxi and into a waiting car not far from the Syrian border.
Rasheed also collected information about ISIS, mapping the locations of homes of Western ISIS fighters in Syria, identifying IP addresses and locations of internet cafes in ISIS-controlled territory, and taking screenshots. conversations he had with IS fighters.
During a conversation, Rasheed spoke to a man suspected of being a notorious British IS fighter and recruiter, Raphael Hostey, who told him: “I need you to work under me. Officially… I want you to help us bring people in.”
In a follow-up text, Rasheed asks Hostey, “Can you explain a bit, please?”
Hostey says, “The same thing you’re doing now, but you’re working for us bringing stuff, bringing brothers and sisters.” Mohammed Al Rasheed replies, “I am ready, brother.”
Rasheed was arrested in the Turkish town of Sanliurfa shortly after facilitating the girl’s journey to Syria.
In a statement to law enforcement, he said the reason he collected information on everyone he helped, including Shamima, was because “I was passing this information to the Canadian Embassy in Jordan”.
Rasheed said that in 2013 he went to the Canadian embassy in Jordan to try to apply for asylum. He said: “They told me that they would grant me my Canadian citizenship if I gathered information on the activities of the Islamic State.”
The BBC was able to confirm that Rasheed traveled in and out of Jordan several times between 2013 and his arrest in 2015.
Tasnime Akunjee, the lawyer for the Begum family, said there will be a hearing in November to challenge the stripping of Begum’s citizenship and that “one of the main arguments” will be that the home minister of At the time, Sajid Javid did not consider her to be a victim of trafficking.
“The UK has international obligations as to how we view a trafficked person and what guilt we impose on them for their actions,” he said.
Akunjee said it was ‘shocking’ that a Canadian intelligence operative was a key part of the smuggling operation – ‘someone who is meant to be an ally, protecting our people, rather than trafficking British children in a war zone.
“Intelligence gathering seems to have taken priority over the lives of children,” he said.
Shamima Begum is currently being held in a detention camp in northeast Syria. His citizenship was stripped from him in 2019 after he emerged from the ashes of IS’ so-called caliphate.
A UK government spokesman said: ‘It has been our long-standing policy not to comment on operational intelligence or security matters.’
Defense Secretary Ben Wallace said he could not “comment on intelligence matters” but added that “at this time” he did not acknowledge “what was being reported”.
Canadian Prime Minister Justin Trudeau said intelligence services need to be “flexible” and “creative in their approaches” to countering terrorism, but “they are bound by strict rules”.
“We will continue to ensure that appropriate oversight is carried out and, if necessary, consider further steps,” he added during a press conference in Ottawa.
A spokesperson for the Canadian Security Intelligence Service said it could not “comment publicly, confirm or deny details of CSIS investigations, operational interests, methodologies or activities”.