The BBC has been banned from identifying a “dangerous extremist and misogynist” who is allegedly an MI5 informant, after a high court judge granted an injunction. The attorney general, Suella Braverman, successfully blocked the identification of the alleged informant, or covert human intelligence source (Chis), referred to as X throughout the proceedings. One woman told the BBC that X had used his status as an agent to abuse, control and coerce her and that MI5 must have known about his behaviour. Another said he might murder someone unless he was exposed. In a ruling on Thursday, Mr Justice Chamberlain said the evidence he had seen, in open court and in closed hearings, had convinced him the injunction was necessary. “The attorney is more likely than not to succeed at trial in establishing that the balance of public and private interests favours the grant of relief prohibiting the BBC from disclosing X’s name and image,” he said. “The BBC will still be able to convey what it regards as the core elements of its story, including the allegation that X abused his Chis status and the allegation that MI5 is at fault for using or continuing to use him as a Chis. The government will be heavily constrained in how it can respond to the latter allegation, but the constraints can be explained.” The BBC went to court this month to try to stop an injunction against a report that would have identified the MI5 agent. The corporation claimed the agent used his status to abuse two ex-partners, and said naming him was in the public interest. The government said identifying him posed a risk to his life and national security. Large parts of a two-day case were heard in closed proceedings, which the BBC was not allowed to attend. The BBC claimed that X used his status as an agent to abuse, control and coerce a former partner, referred to by the pseudonym Beth, and that MI5 either knew or ought to have known about this and was wrong to use him as an agent. Another woman, known by the pseudonym Ruth, who alleges she was abused by X, has said she fears he will kill a woman if he is not “challenged and exposed”. Braverman sought an injunction to block the broadcast, arguing that identifying X would create a “real and immediate risk” of serious or life-threatening harm to him and would damage national security. Lawyers representing Braverman said she “neither confirms nor denies” the BBC’s claim that X is an agent or Chis, but was conducting the hearing on the “hypothetical assumption” that he is or was. The BBC’s legal team told the court: “Beth and Ruth have an intimate insight into X’s psyche and behaviour, making them uniquely placed to evaluate the risk that he poses to other women.” David Pannick, representing the broadcaster, said: “He told one of those women, who we call Beth, that he worked for MI5 in order to terrorise her, in order to control her. The programme will say that MI5 should have known about his behaviours and realised that it was not appropriate to [have] used him as a Chis.” He told the court there was a “particularly strong public interest” in the story given the “current context of public debate” on coercive control of women by male partners. There was “simply no cogent evidence to justify a conclusion that X is at serious risk of serious harm or death” if he is identified, Lord Pannick said. In a witness statement, Beth said: “I think X is a very dangerous individual – to me, to ex-partners and to other women. He thinks it’s OK to treat women the way that he’s treated me. I believe he must be named and identified to the public at large to warn others.” Ruth said in a statement: “I consider that he is dangerous enough to kill a woman and I fear that he will do so if he is not challenged and exposed. I think it is crucial that other women know his identity and what he looks like, so that he cannot trick and harm them.” Sir James Eadie QC, for the attorney general, said: “Publication of the report would constitute a breach of confidence/false confidence by the BBC. To do so would damage national security and the public interest. It would also create a real and immediate risk of serious or life-threatening harm to X.” The attorney general argued there was no objection to a broadcast about the allegations against X and MI5’s use of agents that did not identify him, but claimed that identifying him would be a breach of confidence and infringe X’s human rights. In a statement issued after the ruling, the BBC said the judgment did not prevent it from reporting “key elements” of its story once restrictions are determined, but said the use of “secret procedures” constrained what the judge was able to say about his decision. A spokesperson for the broadcaster said: “The BBC does not fully know the reasons why [identification of X presents a risk to national security] and nor will the public. This is due to the highly unusual fact that a significant proportion of the evidence in this case was heard in a closed hearing, which even the BBC as a party was not permitted to attend. “While we had ‘special advocates’ representing our interests in those closed proceedings, we are not able to know anything about the secret hearing. The reasons the BBC is not able to identify X are largely in the closed judgment, which we cannot inspect. “The secret procedures used in cases like this also constrain what the judge is able to say about his decision in the public judgment. They are a significant departure from the principles of open and natural justice, as the judge himself states.” A spokesman for the attorney general’s Office said: “We welcome today’s judgment.”