MI5 will pay compensation and has apologised to a woman who was coercively controlled and attacked with a machete by one of its agents.

Her legal claim followed a BBC investigation four years ago, which showed that the man, known publicly as Agent X, was a neo-Nazi misogynist who used his security service role as a tool of abuse.

The BBC found he used his status to abuse his partner, known by the alias Beth, before he moved abroad, while under police investigation, to continue intelligence work.

After subsequently failing in court to discredit Beth, MI5 recently offered to pay compensation to settle her claim. She has now accepted the offer.

Kate Ellis, from the Centre for Women's Justice, who is Beth's solicitor, said: "To have this kind of outcome and to win actually against a body like MI5 who are so shrouded in secrecy and in a sense so powerful, is a huge achievement for Beth."

In a statement, MI5's Director General Sir Ken McCallum said: "We sincerely apologise to Beth for the distress she has suffered because of MI5 mistakes in this litigation.

"We relied on incorrect evidence and our record keeping fell well short of the standard of professionalism that we expect, and to which Beth was entitled. We profoundly regret that our mistakes prolonged the litigation and caused additional suffering for Beth.

"MI5 has settled Beth's claim and we have apologised to Beth directly."

"Prompted in part by Beth's case, MI5 has embarked on a programme of work to reinforce the highest standards of record keeping and information management."

MI5 has resolved Beth's legal claim at the Investigatory Powers Tribunal without admission of liability, meaning without a legal admission of wrongdoing.

In 2021, Sir Ken wrongly claimed the planned story was "inaccurate" when he personally contacted his BBC counterpart Tim Davie in a failed effort to undermine the reporting.

Evidence showed the MI5 spy, a foreign national, was a right-wing extremist with a violent past. He also engaged in fantasies about eating children.

He had abused a previous partner abroad, before taking on his MI5 role, including threatening to kill her and her child.

Beth, a British national, met the agent on a dating site. The couple went on to live together in the UK.

She previously told the BBC he was "charming" at first but over time revealed himself to be a misogynist and extremist, obsessed with violence and cruelty. Beth said he sexually assaulted her, and was also abusive and coercive.

One video showed Agent X threatening to kill her and attacking her with a machete.

In a statement, Beth said that she was "grateful" for the compensation, "but it can never do anything to repair what I went through at the hands of X."

"I'd pay that money so as not to have to experience even a minute of what I had to experience of the worst of his abuse."

She added that she feels "very strongly that, despite this apology, the MI5 are still protecting this violent misogynistic predator."

MI5 is currently under investigation after the BBC revealed that the security service gave false evidence to three courts while defending its handling of the agent.

The inquiry, by the investigatory powers commissioners, is due to report to Prime Minister Sir Keir Starmer within weeks.

Arguing for secrecy, the security service told judges it had stuck to its policy of not confirming or denying informants' identities.

In fact, MI5 had disclosed the Agent X's status in phone calls to me, as it tried to persuade me not to investigate him. The service aggressively maintained its position until I produced evidence proving it was untrue, including a recording of one of the calls.

Following the BBC's revelations last February, Sir Ken apologised for the false evidence.

Two official inquiries then took place which absolved MI5 and its officers of deliberate wrongdoing, claiming the false evidence was down to mistakes and poor memories.

But, in July, a panel of senior high court judges ruled that the "investigations carried out by MI5 to date suffer from serious procedural deficiencies" and that "we cannot rely on their conclusions".

They said it would be "premature" to decide whether to begin contempt of court proceedings against any MI5 officers before a new investigation took place.

Sir Ken previously said the service would co-operate fully with the new inquiry.