Three men, including the two suspects shot by police at the scene of the murder of the soldier Lee Rigby, remained under arrest in connection with the killing.
Scotland Yard said two women arrested in London on suspicion of conspiracy to murder had been released without charge.
One of the women, aged 29, was arrested at the same time as a man of the same age during a raid on a housing block in Greenwich in the early hours of Thursday.
The man last night remained in custody on suspicion of conspiracy to murder. The second woman, 31, understood to be a relative of the suspected murderer Michael Adebowale, was arrested shortly before midnight on Thursday. She was released Friday morning.