Detectives hunt for possible associates of Westminster killer Khalid Masood

Counter-terrorism detectives are attempting to trace any associates of Khalid Masood as they mount a huge investigation to establish what triggered the terrorist's murderous rampage in Westminster.

Eleven people have been arrested as part of the inquiry but Scotland Yard said only four remain in custody - two men aged 27 and 58 who were arrested in Birmingham on Thursday and a 32-year-old woman and a 35-year-old man who were arrested in Manchester on Friday.