Shamima Begum’s family have said they were “shocked and appalled at the vile comments” the Isis bride has made since re-emerging into the public eye – but pleaded for Sajid Javid’s help to bring her infant son to Britain.

The teenager’s sister, Renu, wrote to the home secretary on Thursday to say the family planned to challenge his decision to strip Ms Begum of her British citizenship and that her potential return was “a matter for our British courts to decide”.

Family members said they had lost the now-19-year-old to a “murderous and misogynistic cult” that had exploited her and “fundamentally damaged her”, leading to the “sickening” comments she has made in recent interviews, including the suggestion that the Manchester Arena bombing was “justified”.

Renu Begum’s letter said: “As a family man yourself, we hope you will understand that we, as her family cannot simply abandon her.

“We have a duty to her, and a duty to hope that as she was groomed into what she has become, she can equally be helped back into the sister I knew, and daughter my parents bore.”

Timeline of the Isis caliphate Show all 19 1 /19 Timeline of the Isis caliphate Timeline of the Isis caliphate ISIS began as a group by the merging of extremist organisations ISI and al-Nusra in 2013. Following clashes, Syrian rebels captured the ISIS headquarters in Aleppo in January 2014 (pictured) AFP/Getty Timeline of the Isis caliphate Abu Bakr Al-Baghdadi declared the creation of a caliphate in Mosul on 27 June 2014 Timeline of the Isis caliphate Isis conquered the Kurdish towns of Sinjar and Zumar in August 2014, forcing thousands of civilians to flee their homes. Pictured are a group of Yazidi Kurds who have fled Rex Timeline of the Isis caliphate On September 2 2014 Isis released a video depicting the beheading of US journalist Steven Sotloff. On September 13 they released another video showing the execution of British aid worker David Haines Timeline of the Isis caliphate The US launched its first airstrikes against Isis in Syria on 23 September 2014. Here Lt Gen William C Mayville Jnr speaks about the bombing campaign in the wake of the first strikes Getty Timeline of the Isis caliphate Isis militants sit atop a hill planted with their flag in the Syrian town of Kobani on 6 October 2014. They had been advancing on Kobani since mid-September and by now was in control of the city’s entrance and exit points AFP/Getty Timeline of the Isis caliphate Residents of the border village of Alizar keep guard day and night as they wait in fear of mortar fire from Isis who have occupied the nearby city of Kobani Getty Timeline of the Isis caliphate Smoke rises following a US airstrike on Kobani, 28 October 2014 AFP/Getty Timeline of the Isis caliphate YPG fighters raise a flag as they reclaim Kobani on 26 January 2015 VOA Timeline of the Isis caliphate Isis seized the ancient Syrian city of Palmyra on 20 May 2015. This image show the city from above days after its capture by Isis Getty Timeline of the Isis caliphate Kurdish forces are stationed on a hill above the town of Sinjar as smoke rises following US airstrikes on 12 November 2015 AFP/Getty Timeline of the Isis caliphate Kurdish forces enter Sinjar after seizing it from Isis control on 13 November 2015 AFP/Getty Timeline of the Isis caliphate Iraqi government forces make the victory sign as they retake the city of Fallujah from ISIS on 26 June 2016 Getty Timeline of the Isis caliphate Iraqi forces battle with Isis for the city of Mosul on 30 June 2017 AFP/Getty Timeline of the Isis caliphate Members of the Iraqi federal police raise flags in Mosul on 8 July 2017. On the following day, Iraqi prime minister Haider Al Abadi declares victory over Isis in Mosul Getty Timeline of the Isis caliphate Members of Syrian Democratic Forces celebrate in Al-Naim square after taking back the city of Raqqa from Isis. US-backed Syrian forces declare victory over Isis in Raqqa on 20 October 2017 after a four-month long campaign Getty Timeline of the Isis caliphate Female fighters of the Syrian Democratic Forces celebrate in Al-Naim Square after taking back the city of Raqqa from Isis. US-backed Syrian forces declare victory over Isis in Raqqa on 20 October 2017 after a four-month long campaign AFP/Getty Timeline of the Isis caliphate Trucks full of women and children arrive from the last Isis-held areas in Deir ez-Zor, Syria in January 2019 They were among the last civilians to be living in the ISIS caliphate, by this time reduced to just two small villages in Syria’s Deir ez-Zor Richard Hall/The Independent Timeline of the Isis caliphate Zikia Ibrahim, 28, with her two-year-old son and 8-month-old daughter, after fleeing the Isis caliphate, on Saturday 26 January 2019 Richard Hall/The Independent

It added: “We were pleased to learn from your comments in the Commons that you recognise my nephew, Shamima’s son, as a British citizen.

“As a family, we ask now how we can assist you in bringing my nephew home to us.

“In all of this debacle, he is the one true innocent and should not lose the privilege of being raised in the safety of this country.”

It came after Jeremy Corbyn said Ms Begum should be repatriated to the UK, four years after she left aged 15 to join Isis.

The Labour leader criticised Mr Javid’s decision to strip her citizenship as “very extreme”, adding: “She obviously has, in my view, a right to return to Britain.

“On that return she must obviously face a lot of questions about everything she has done and at that point any action may or may not be taken.”

The Begum family’s lawyer, Tasnime Akunjee, has also called on Mr Javid to explain what steps could be taken to bring Ms Begum’s son to Britain.

The home secretary has been accused of making Ms Begum stateless after Bangladesh, where her parents were born, said there was “no question of her being allowed to enter” the country.

Shahriar Alam, Bangladesh’s foreign minister, said its government was “deeply concerned that [Ms Begum] has been erroneously identified as a holder of dual citizenship”.

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Ms Begum is one of 150 people stripped of their UK citizenship for the “public good” since 2010.