A man has been charged with terrorism offences over the alleged possession of a document by Anwar al-Awlaki, the al-Qaida preacher who was killed last year by a US drone strike in Yemen.
Mohammed Shabir Ali, 24, of east London, is accused of possessing 44 Ways to Support Jihad between 20 August 2008 and 21 June 2011.
The Metropolitan police said that the document was "of a kind likely to be useful to a person committing or preparing an act of terrorism".
Ali has also been charged with intending, during the same period, to assist another person to commit acts of terrorism.
Ali, who was arrested on Monday, will appear at Westminster magistrates' court on Wednesday.
A Scotland Yard spokesman said two men, aged 24 and 30, and a 21-year-old woman, remained in police custody following their arrest on Monday.
The woman and the 30-year-old man were arrested at residential addresses in east London while the 24-year-old man was arrested at a business address in west London.
Awlaki, a US-Yemeni radical Muslim cleric, was linked to a series of attacks and plots around the world, including the shootings at Fort Hood, Texas, in November 2009, and the activities of the 'underwear bomber', Umar Farouk Abdulmutallab.
US officials had described Awlaki as a key figure in al-Qaida in the Arabian Peninsula (AQAP) and regarded his death as a milestone in the fight against al-Qaida. He was reported to have been tracked for several days before a drone fired missiles at the car in which he was travelling on 30 September 2011.