Helping Shamima Begum return to Britain would “open the floodgates” for other Isis members, a former terror police chief has warned.

Scott Wilson said the 19-year-old “made the choice” to join Isis in Syria and must suffer the consequences, amid debate about the fate of her newborn son.

The retired officer, who was UK national counterterrorism coordinator for protect and prepare until July, told journalists: “If the government starts making a freeway to get back from Syria, where does it stop?

“If you make it easy then you’ll just open the floodgates and suddenly there will be multiple people.”

Suspected Isis fighter Jack Letts, known as Jihadi Jack, also said he wants to return to the UK in an interview from Syria last week.

Syria at war: Fleeing the caliphate Show all 14 1 /14 Syria at war: Fleeing the caliphate Syria at war: Fleeing the caliphate Trucks full of women and children arrive from the last Isis-held areas in Deir ez-Zor, Syria Richard Hall/The Independent Syria at war: Fleeing the caliphate Zikia Ibrahim, 28, with her two-year-old son and 8-month-old daughter, after fleeing the Isis caliphate Richard Hall/The Independent Syria at war: Fleeing the caliphate Trucks full of women and children arrive from the last Isis-held areas in Deir ez-Zor, Syria. Richard Hall Richard Hall/The Independent Syria at war: Fleeing the caliphate Men who fled the last Isis-held area of Syria line up to be questioned by American and Kurdish intelligence officials Richard Hall/The Independent Syria at war: Fleeing the caliphate Trucks full of women and children arrive from the last Isis-held areas in Deir ez-Zor, Syria. Richard Hall Richard Hall/The Independent Syria at war: Fleeing the caliphate A young girl pulls her belongings after arriving Richard Hall/The Independent Syria at war: Fleeing the caliphate An SDF fighter hands out bread to women and children after they arrive Richard Hall/The Independent Syria at war: Fleeing the caliphate Sita Ghazzar, 70, after fleeing from the last Isis-held territory in Syria Richard Hall/The Independent Syria at war: Fleeing the caliphate A family from Russia who recently fled the last Isis-held area of Syria Richard Hall/The Independent Syria at war: Fleeing the caliphate Trucks full of women and children arrive from the last Isis-held areas in Deir ez-Zor, Syria. Richard Hall Richard Hall/The Independent Syria at war: Fleeing the caliphate Trucks full of women and children arrive from the last Isis-held areas in Deir ez-Zor, Syria. Richard Hall Richard Hall/The Independent Syria at war: Fleeing the caliphate Trucks full of women and children arrive from the last Isis-held areas in Deir ez-Zor, Syria. Richard Hall Richard Hall/The Independent Syria at war: Fleeing the caliphate Trucks full of women and children arrive from the last Isis-held areas in Deir ez-Zor, Syria. Richard Hall Richard Hall/The Independent Syria at war: Fleeing the caliphate Richard Hall Richard Hall/The Independent

It was also reported that Islamist cleric Abu Hamza’s son, Sufyan Mustafa, is fighting the decision to revoke his British passport.

Mr Wilson said police and security services were spending “millions” monitoring extremists already in the UK, and that if Ms Begum was allowed to return she would have to be watched for years.

“They will never be able to take their eyes off her because they don’t know what could happen,” he added. “If she did do something in the UK then the security services and government would be blamed.”

He was speaking at a briefing ahead of the Security & Counter Terror Expo 2019, where another officer warned that it was “only a matter of time” before another attack.

Chief Inspector Pete Dalton, head of protection at Thames Valley Police, said that with a record 700 terror investigations ongoing nationally, the attack threat had not gone away.

“Complacency is a real risk,” he added. “It’s a real risk in the professional security industry, in terms of budgets and cost. It’s a risk in terms of mindset.

“There’s still lots of work to be done and sadly it’s only a matter of time before another incident happens.”

(Statista (Statista)

She is among 20 British women and children being held in camps by the Syrian Democratic Forces, along with six suspected fighters, The Independent understands.

Ms Begum’s family lawyer accused the government of making her stateless and vowed to appeal the decision, and Bangladesh denied the teenager was a dual national.

Her family have written to the home secretary asking for his help to bring her newborn son to Britain.

Ms Begum’s sister, Remu, asked how they could help the government “in bringing my nephew home to us”.

Jeremy Corbyn is among politicians saying Ms Begum has the right to return to Britain, but Mr Wilson said there “must be consequences” for joining Isis.

“People are trying to say she was a groomed child but … she planned it herself, nobody dragged her onto that plane, no one kidnapped her and put her there,” he added.

“She went with the clear intention to join Isis and if it hadn’t ended up the way it had, she probably would have stayed there.

Jeremy Corbyn says Shamima Begum has ‘right to return’ to UK and face questioning

“Now she doesn’t like where she has ended up and she wants to come back – we can’t have that.”

Ms Begum and the two friends she travelled to Syria with had been interviewed by the Metropolitan Police after a fourth friend from Bethnal Green Academy fled to join Isis months before.

Terri Nicholson, a former Metropolitan Police counterterrorism officer, said officers “spent tremendous effort on trying to stop people travelling to Syria in the first place”.

“Because the consequences aren’t just for [Ms Begum], they’re for her family left behind, her now young baby,” she added.

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Ms Nicholson acknowledged there were a “lot of unknowns” to balance when removing extremists’ citizenship, following warnings that the practice can effectively set terrorists free in warzones without any monitoring.

“But if that individual does return it’s a distraction at a time when security and intelligence agencies are at full tilt,” she added.