A Canadian intelligence agent smuggled Shamima Begum and her two friends into Syria, according to reports.
Ms Begum fled her east London home for Syria as a 15-year-old schoolgirl with Kadiza Sultana and Amira Abase to join the so-called Islamic State group (IS) more than seven years ago.
She has denied any involvement in terror activities and is challenging a Government decision to remove her citizenship, while Ms Sultana was reportedly killed in a Russian air raid and Ms Abase is missing.
According to the BBC and The Times, Mohammed Al Rasheed, who is alleged to have been a double agent working for the Canadians, met the girls in Turkey before taking them to Syria in February 2015.
A spokesman for the UK Government said: “It is our longstanding policy that we do not comment on operational intelligence or security matters.”
A spokesman for the Canadian Security Intelligence Service added: “I cannot publicly comment on or confirm or deny the specifics of CSIS investigations, operational interests, methodologies, or activities.”
In a forthcoming podcast for the BBC, called I’m Not A Monster, Ms Begum is quoted as saying: “He (Rasheed) organised the entire trip from Turkey to Syria… I don’t think anyone would have been able to make it to Syria without the help of smugglers.
“He had helped a lot of people come in… We were just doing everything he was telling us to do because he knew everything, we didn’t know anything.”
In February 2019, Ms Begum was found, nine months pregnant, in a Syrian refugee camp. Her British citizenship was revoked on national security grounds shortly afterwards.
She challenged the Home Office’s decision but the Supreme Court ruled that she was not allowed leave to enter the UK to pursue her appeal.
She added that she had been “groomed” to flee to Syria as a “dumb” and impressionable child.
Begum family lawyer Tasnime Akunjee said in a statement: “In November, Shamima Begum will have a hearing in the SIAC (Special Immigration Appeals Commission) court, where one of the main arguments will be that when former Home Secretary Sajid Javid stripped Shamima Begum of her citizenship leaving her in Syria, he did not consider that she was a victim of trafficking.
“The UK has international obligations as to how we view a trafficked person and what culpability we prescribed to them for their actions.
“If the BBC has evidence of a trafficking network, and Shamima Begum being a victim of that network, then it will certainly have an impact on the hearing in November. The most shocking element of this is that integral to that traffic network were the actions of a Canadian intelligence asset. Someone who is supposed to be an ally protecting our people rather than trafficking British children into a war zone.
“Intelligence gathering looks to have been prioritised over the lives of children.
“Britain has lauded its efforts to stop Isis and the grooming of our children by spending millions of pounds on the Prevent program and online monitoring. However, at the very same time, we have been cooperating with a Western ally, trading sensitive intelligence with them whilst they have effectively been nabbing British children and trafficking them across the Syrian border for delivery to Isis, all in the name of intelligence gathering.
“The calculation here is that the lives of British children, and the risk of their death, is part of the algorithm of acceptable risk that our Western allies have taken.”