SAJID Javid has warned he "will not hesitate" to prevent the return of Britons who have travelled to join Islamic State as the debate flared over what should happen to the onetime runaway schoolgirl Shamima Begum.

The Home Secretary made clear that those who left the UK to join IS/Daesh were "full of hate for our country" while Ben Wallace, the Security Minister, warned that runaways who now wanted to come back must realise that "actions have consequences".

Ms Begum's family have pleaded for the 19-year-old, who is heavily pregnant, to be shown mercy and to be allowed to return to east London.

Speaking at a refugee camp in northern Syria, Ms Begum said she would "do anything required just to be able to come home and live quietly with my child".

Her case has received high-profile backing with a former MI6 chief saying the teenager should be given a chance "if we are to stand by our values".

Meanwhile, Anthony Loyd, The Times correspondent who found Ms Begum, said she was a "15-year-old schoolgirl who made a terrible mistake...and we must do our best to rehabilitate her amongst our own people".

But her plea has been strongly rejected by others - including the brother of Alan Henning, the British aid worker beheaded by Jihadi John, who said she should "absolutely not" be allowed back.

Mr Javid said: "We must remember that those who left Britain to join Daesh were full of hate for our country.

"My message is clear: if you have supported terrorist organisations abroad, I will not hesitate to prevent your return. If you do manage to return you should be ready to be questioned, investigated and potentially prosecuted."

Any hopes of a rescue mission by British officials were swiftly quashed on Thursday as the Government ruled out an effort inside Syria to assist Ms Begum.

While refusing to comment on individual cases, Mr Wallace said: "I'm not putting at risk British people's lives to go and look for terrorists or former terrorists in a failed state.

"There's consular services elsewhere in the region and the strong message this Government has given for many years is that actions have consequences."

While no official operation to remove Ms Begum from Syria will be carried out, questions have been raised over whether Britain would be able to prevent Ms Begum's eventual return to the UK.

Lord Carlile, the former independent reviewer of terrorism legislation, told the BBC that if Ms Begum had not gained a second citizenship of another country, she would have to be allowed back to her homeland because under international law it was not possible for a person to be made "stateless".

Meanwhile, Richard Barrett, a former director of global counter-terrorism at MI6, suggested it would be "unreasonable" to expect the Syrian Defence Force to look after her indefinitely.

He also warned that summary execution was the "most likely outcome" for such captured foreign nationals who were handed over to Syrian or Iraqi authorities.

Writing for The Guardian, he said: "Governments have a responsibility to address the problems created by their captured nationals and also to look more closely at why they made the choices they did."

He added: "Even [Ms Begum], as unrepentant as she may be, should be given a chance, if we are to stand by our values and if we believe our society is strong enough to reabsorb a 15-year-old who went badly off the rails."

Ms Begum's admission that she did not regret travelling to IS-controlled Syria, and her assertion that she is "not the same silly little 15-year-old schoolgirl who ran away from Bethnal Green four years ago" has been highlighted as a cause for concern by some.

Dr Kim Howells, a former counter-terrorism minister, noted: "She sounds to be completely unrepentant, she sounds cynical."

Mr Henning's brother Reg told The Sun: "The authorities should take her passport off her. She made her choice, didn't she? She made her bed and she should lie in it."

However, Ms Begum's brother-in-law Mohammed Rehman said her family wanted her to be allowed to return and be "re-educated".

He said: "I can understand why people in this country are angry and don't want her back. What she's done doesn't portray Islam in a good light. But she was only 15 when she went to Syria. We are appealing for compassion and understanding on her behalf."

Ms Begum was one of three schoolgirls, along with Kadiza Sultana and Amira Abase, from Bethnal Green Academy who left the UK in February 2015.

Another girl, Sharmeena Begum, also from Bethnal Green but not related to Shamima, had travelled to Syria two months earlier.

Ms Sultana was reported to have been killed in an air strike in 2016.

Ms Beum said she had recently heard second-hand that the other two girls could still be alive.

Meanwhile, Sadiq Khan, the London Mayor, said the authorities needed to speak to Ms Begum if she intended to return to the UK.

"As far as this individual person is concerned, what's important is for the authorities, that means the police, that means the other authorities, to speak to her if she decides to ever return to the UK, to consider whether any criminal offences have been committed.

"If they have then it's really important that, following due process, she faces a trial. And we will have to wait and see what happens in relation to that.

“It's really important though for me as someone who is a public figure not to inadvertently prejudice a future trial," he stressed.