Britain’s domestic security agency MI5 has acknowledged providing three courts with evidence based on false information while attempting to conceal the identity of a violent neo-Nazi informant, the BBC reported Friday.

MI5's lawyer Timothy Otty told London's High Court that the agency "accepts without reservation" the findings of an investigation that concluded senior officers provided false evidence about whether it had maintained its secrecy policy, known as "neither confirm nor deny."

The case concerns an MI5 informant known as Agent X, who coercively controlled and abused his partner, identified by the alias Beth, including attacking her with a machete, the BBC reported.

An investigation by former Deputy Investigatory Powers Commissioner John Goldring found "serious and systemic failures in MI5's conduct," concluding that one senior officer repeatedly provided false information while another misled colleagues and lied about information he had received.

A panel of three senior judges is now considering whether contempt of court proceedings should be brought against individual MI5 officers or the security service itself, a step the BBC said would be unprecedented.

MI5 said one officer had resigned and another had been suspended pending disciplinary proceedings.

Otty argued against contempt proceedings, citing MI5's apologies and a reform program being carried out under Director General Ken McCallum.