At least three Bangladeshis have been fighting a legal battle to win back their British citizenship rights after being stripped of their passports on suspicion of alleged extremist activity.

A UK-born man and woman, known only as E3 and G3 for legal reasons, and a third Bangladesh-born British man N3, are among 100 people stripped of British nationality last year on national security grounds.

E3, a 37-year-old man, was born in the UK to Bangladeshi parents and received the order in June 2017 on suspicions of Islamist extremism. But his lawyers claim he had simply been working in Britain to support his family in Bangladesh and had his citizenship removed while visiting Bangladesh for the birth of his second child.

N3 has three British children living in the UK and was deprived of his citizenship after travelling to Turkey for a few weeks in October 2017. His lawyers claim the 35-year-old, born in Bangladesh, was in Turkey for business and currently remains stranded there.

UK-based Duncan Lewis Solicitors said both men were targeted on national security grounds days before they were due to return to the UK, and have been left “stranded in foreign countries without any source of income or support”.

London-born G3 was alleged to be an Islamic State (ISIS) member and was detained by Turkish authorities on the Syrian border with her two young children in 2016.

The UK government had argued that because they were dual British-Bangladeshi nationals, the deprivation orders on national security grounds would not render them stateless. However, the Special Immigration and Appeals Commission, in a secret hearing earlier this month, concluded that the deprivation orders had in fact rendered them stateless, which was in breach of international law.

The commission found that Bangladeshi law required them to apply to retain their citizenship at 21, but they failed to do so and were therefore left with only British nationality.

“We intend to appeal this judgment. As such, it would not be appropriate to comment further,” a UK Home Office spokesperson said.

While international law stipulates that people cannot be left stateless, the UK Immigration Act 2014 introduced a power allowing that to happen if a person has “acted in a manner seriously prejudicial to the vital interests of the UK”. The British government’s 2018 Transparency Report on Disruptive and Investigatory Powers had noted that this action may only be taken if the Home Secretary had reasonable grounds for believing that the person is able, under the law of a country outside the UK, to become a national of that country.

The conclusion of these legal challenges is expected to determine the future use of this measure.