The New IRA has admitted responsibility for the murder of journalist Lyra McKee in Derry last week as police made a new arrest in connection with the killing.

McKee, 29, was shot in the head while reporting on rioting in the Creggan area on Thursday night and later died from her injuries.

Her last tweet, sent just minutes before she was shot, said: “Derry tonight. Absolute madness,” accompanied by a picture of smoke rising from the scene.