Missing Syria schoolgirls: Four more pupils at Bethnal Green Academy being monitored over fears they considered joining Isis

Four more pupils at the east London school attended by three teenage girls who travelled to Syria are being monitored over fears they may also have been considering leaving Britain to join Islamic State.

The Independent understands that a total of seven students at the Bethnal Green Academy, including the trio who succeeded in travelling out of Britain last month, were identified by police as being potentially vulnerable to radicalisation as early as December last year after a fellow pupil travelled to Syria.

The girls are believed to have been placed on a warning list as part of the Government’s Prevent strategy to counter radicalisation after their classmate managed to board a flight to Turkey from a London airport.

The continuing concern over teenagers being lured to join ISIS came as relatives of the three girls who left for Syria said they believed police had “let them walk out” of Britain after it emerged they had been spoken to by officers twice before their disappearance.

Relatives of the teenagers told Vice News website that each of the girls had received letters from counter-terrorism detectives seeking permission from their parents for statements about the disappearance of their classmate in December to be taken shortly before they themselves left for Syria on 17 February.

The parents never received the letters and said they were not informed that their daughters - Shamima Begum, Amira Abase, both 15, and 16-year-old Kadiza Sultana - had been spoken to in school by officers. Now the families fear the intervention may have hastened the girls’ decision to leave.

Fahmida Aziz, a cousin of Ms Sultana, said: “Were they feeling victimised by police? Were they feeling criminalised? Did they feel they had done something wrong? My query would be, by giving this letter, how did that make the girls feel?”

The Yard has insisted that it had no evidence that the three girls were at risk of fleeing to Syria prior to their departure. The letters, dated 2 February, underlined that the teenagers were “not under any suspicion of doing something wrong”.

Sources with knowledge of the ongoing investigation said that the four girls now being monitored are the remainder of the seven who were all informally interviewed by police when the unnamed Bethnal Green Academy pupil, aged 15, made the journey to Syria in December after apparently answering the siren call of ISIS recruiters.

The four, who also received the letters, are continuing to attend lessons at the school, which is rated as outstanding by Ofsted and has been told by police there is no evidence radicalisation took place within its walls, while their families receive support from police and the local authority.

It is understood that detectives have examined mobile phones belonging to the quartet to look at their contacts with the three other teenagers prior to 17 February. One line of inquiry is believed to be the theory that the girls who travelled to Syria were directly assisted by an ISIS facilitator based in Britain.

Relatives of the three departed girls said they felt they should have been told by both police and the school that they had been approached by detectives and that officers may have been able to do more to prevent their departure from Britain.

Jubeyda Rauf, the 16-year-old sister of Ms Sultana, said: “I just feel like the police allowed that to happen. It seemed like they had more information, they knew what they were doing. I just feel like they let them walk out. That’s how it feels.”

The official leading anti-radicalisation efforts in the London borough of Tower Hamlets, where the Bethnal Green Academy is based, also criticised the Yard’s initial investigation into the disappearance of the first teenager.

Nojmul Hussain, manager of the Prevent scheme in Tower Hamlets, told Vice News: “No risk assessments were done around how they could support other students who came into contact with the girl. There are a lot of lessons that must be taken from the way the investigation was handled, the main one being the value of information sharing from the outset.”

The Yard acknowledged its contact with the three teenagers but insisted its enquiries had been routine. In a statement, it said: “There was nothing to suggest at the time that the girls themselves were at risk and indeed their disappearance has come as a great surprise, not least to their own families.

“The girls were spoken to in December 2014 as part of the routine inquiry by officers investigating the disappearance of their friend. We continue to liaise with the school and local education authority in connection with this ongoing investigation.”

The Bethnal Green Academy did not respond to a request for comment.