A man whose British citizenship was removed due to alleged links to the Manchester Arena bombing has had it returned to him by Home Secretary Priti Patel, the BBC can reveal.
The man's citizenship was removed in the aftermath of the attack in 2017.
The original decision was taken by Amber Rudd when she was home secretary.
Twenty-two people were killed and hundreds were injured when Salman Abedi detonated a bomb at the end of an Ariana Grande concert on 22 May 2017.
The mother of one of those murdered said bereaved families "need answers" from the home secretary.
The man, who cannot be named for legal reasons, had appealed against the original decision to remove his citizenship at the Special Immigration Appeals Commission (SIAC), but the case has not proceeded to a full hearing.
A SIAC document, provided to the BBC, reveals Ms Patel instead "decided to withdraw the decision to deprive the appellant of his British citizenship".
It was decided in July 2017 that stripping his British citizenship was conducive to the public good.
It was alleged the man was an associate of Salman Abedi, might have known about the bombing beforehand, and might have helped in its preparation.
The man contended that he was subjected to ill treatment outside the UK.
Ms Patel informed the court by letter on 25 June this year of her decision, with the move confirmed the following month.
No reasons have been publicly given.
A Home Office spokesperson said: "The government, working with our world-class police and security and intelligence agencies, will always take the strongest action possible to protect national security and public safety."
Families of the 22 people murdered in the bombing were not informed of the development.
Caroline Curry, whose 19-year-old son Liam was killed in the attack, told the BBC that "the secrets have got to stop".
She said "we need answers from Priti Patel".
SIAC is a semi-secret court and is the venue of appeal for foreign nationals (or those deprived of British citizenship who are deemed also to have foreign nationality) who face detention, deportation or exclusion from the UK on grounds of national security.
Many of the court's hearings and rulings are never made public, even to the appellants themselves, because they include sensitive evidence which the government says it cannot divulge.
This week, at the public inquiry into the bombing, it emerged that:
- the elder brother of the bomber fled the UK in order to avoid giving evidence
- a friend of the attacker was arrested trying to leave Britain and brought to court in custody
- and a serving terrorist prisoner was also forced to appear after declining to answer questions
Next week, evidence will be heard from MI5 before the inquiry enters three weeks of secret hearings about what the security service knew in advance about the bomber. The victims' families are excluded from the hearings.