The government does not know how many Britons who left to fight for Islamic State a decade ago are still in Syria today, it has emerged.
According to the Home Office, a quarter of the around 900 British citizens who have moved to the region since 2013 have yet to return.
The whereabouts of more than 200 of them are unknown. A 2018 report referring to individuals as having a 'national security problem' claimed that 20 percent had been killed abroad and 40 percent had returned to Britain.
Maya Foa, executive director of human rights organization Reprieve, said The times the government needs to know who the potentially dangerous people are who are still at large.
“They need to know how many of these supposedly dangerous people, who are British or who have traveled from Britain to Syria, are left,” she said.
“They are said to pose this risk, so the government needs to know who they are and where they are, and then take all steps to assess and understand that risk.”
British jihadist woman Shamima Begum pictured with her one-week-old son Jerah at the Al Hawl camp for captured ISIS women with children, Kurdish Syria. Not dated
Islamic State group fighters parade in an Iraqi security forces armored vehicle in the northern city of Mosul, Iraq, June 23, 2014
Hundreds of Britons left the country to join the Islamic State's fight in Syria from 2013.
Many were held in prisons in Turkey and Kurdish prisons.
The Peshmerga, the standing army of the Kurds, played a crucial role in taking down ISIS – and are believed to have around 10 to 15 British men in its prisons, according to Reprieve.
In 2017, there were more than 150 suspended jihadists and criminals stripped of their British citizenship and are not allowed to return to Britain.
Citing official figures and security sources, the Sunday Times reported that in 2017 alone, more than 40 suspects had their passports revoked.
They included armed men and “jihadist brides” traveling to Syria, it added.
According to The Times, there are now an estimated 20 so-called jihadist brides and 40 children in two camps in northern Syria.
According to Ms Foa, most people in the camps are under the age of ten.
Not everyone rejected the return of foreign fighters. The United States, Canada and Australia are among those that have tried to repatriate people who have gone to Syria.
The Daily Mail reported last week that dozens of jihadist brides like Shamima Begum could now return to Britain, as America steps up pressure on ministers to accept them back into Britain.
A source said: 'We believe there could be dozens of these women and they would all need to be monitored 24/7 by a team of specialist police officers, which would be a huge drain on resources.'
Ms Begum was 15 when she and two other east London schoolgirls fled to join ISIS in February 2015. Ten days after arriving in Syria, she married a 23-year-old ISIS fighter.
Her British citizenship was revoked by former Home Secretary Sajid Javid on national security grounds shortly after she was found nine months pregnant in a Syrian refugee camp in February 2019.
She now continues to seek repatriation to Britain, while her lawyers vow to challenge the decision to revoke her citizenship, citing “credible” evidence that she was a victim of human trafficking.
Men suspected of ties to the Islamic State (IS) group gather in a prison cell in the northeastern Syrian city of Hasakeh on October 26, 2019.
Ms Begum, now 23, filed a complaint against the Home Office with the Special Immigration Appeals Commission (SIAC), where her lawyers argued she should be allowed to return to Britain on the grounds that she is a 'victim of child sex trafficking' used to be.
The Home Office defended the decision, saying the security services “continue to assess” she poses a risk to Britain.
MailOnline has contacted the Ministry of Foreign Affairs for comment.
The Ministry of the Interior has not commented.