The FBI is investigating communications between Major Nidal Hasan, who killed 13 people at the Texas army base last week, and Imam Anwar al-Awlaki, a U.S.-born Muslim cleric now based in Yemen.
al-Awlaki, 38, who described Major Hasan on his blog as "a hero," has been a regular visitor to Britain and delivers frequent lectures to British audiences by video or via the internet.
Counter-terrorism sources said yesterday that al-Awlaki was barred from entering Britain on security grounds while the anti-extremist Quilliam Foundation said he was "perhaps the most influential pro-jihadist ideologue preaching in English today."
Despite his extremist reputation, the cleric had attracted support from mainstream British Muslim groups. Azad Ali, president of the Civil Service Islamic Society, wrote last November that al-Awlaki was "one of my favorite speakers and scholars."
Ali, whose society's patron is Sir Gus O'Donnell, the Cabinet Secretary, distanced himself from the cleric's views last night. He said: "I reject them and disassociate myself from them completely."