On Thursday, the Court of Appeal ruled that Begum – one of three east London schoolgirls who travelled to Syria to join Isis – should be allowed to return to the UK to fight the decision to remove her British citizenship.
Downing Street said the Government was “bitterly disappointed” by the ruling and the Home Office said it plans to appeal.
On Friday, Khan said: “People who commit criminal offences must face the music.
“While we’ve got courts in this country and judges who are some of the fairest in the world, I think if a British citizen commits an offence here or overseas they should face justice in the criminal courts.
“And if she has committed a criminal offence I’m sure the jury will find her guilty, and justice will be served.
“What I’m not in favour of is us sub-contracting justice to another country.”
Mr Khan’s comments come after the Begum family lawyer said she could still be a threat if allowed to return to the UK.
Shamima Begum's family lawyer Tasnime Akunjee says only the facts should be considered in her case.
He says she should face the accusations of joining a terrorist organisation in a UK court and be found guilty or innocent.
Watch the whole debate👉https://t.co/fzcHkA6S4k pic.twitter.com/1oPhSsjx1E
— Good Morning Britain (@GMB) July 17, 2020
Tasnime Akunjee told Good Morning Britain: “No one can be sure, including her family, that that won’t happen but that is pure speculation and what we deal with here is facts, is what is the person’s status right now, what have they done right now, and then accuse them formally of those crimes.”
“She had joined a terrorist organisation, albeit at the age of 15. Now that being the case, that’s a criminal offence and an accusation, a criminal accusation, should be levied at her, evidence brought and then a jury of her peers listens to the evidence and then finds her guilty or innocent.”
Begum, now 20, married a Dutch convert shortly after arriving in Syria and said she has given birth to three children, though all have since died.
She has said she regrets her actions and was “brainwashed” by Isis.
Sajid Javid revoked Begun’s citizenship in 2019 on national security grounds. She remains at the al-Roj camp in Syria, insisting the former home secretary’s decision leaves her stateless and exposes her to real risk of death.
Among those also concerned about her return is Richard Walton, the former head of Counter Terrorism Command at the Metropolitan Police, who has said the charges that might be brought against Begum may end up being “relatively minor”, such as membership of a proscribed group.
He warned efforts to prove more serious allegations could be hampered by the difficulty of collecting evidence from war-torn Syria.
That could then lead to issues when she came to be released, Walton added.
He told LBC the Court of Appeal had made a “profound mistake which will have serious ramifications for our security and set a dangerous precedent” and interfered in the state’s duty to protect the public.
He suggested a “workable” treason law should be considered.
After the court ruled Begum should be allowed to return to the UK to challenge the revocation of her citizenship, the prime minister’s spokesman said: “The government’s priority is maintaining our national security, and decisions to deprive individuals of their citizenship are not taken lightly.
“We will always ensure the safety and security of the UK and will not allow anything to jeopardise this.”