Anjem Choudary, Britain's most high-profile Islamist preacher whose followers have been linked to numerous plots across the world, has been found guilty of inviting support for Islamic State.
Choudary, 49, was convicted at London's Old Bailey court of using online lectures and messages to encourage support for the banned group which controls large parts of Syria and Iraq.
Notorious in Britain where the tabloids denounce him as a hate preacher, he is also well-known abroad, making regular TV appearances in the wake of attacks by Islamist militants to blame Western foreign policy for targeting Muslims.
"These men have stayed just within the law for many years, but there is no one within the counter terrorism world that has any doubts of the influence that they have had, the hate they have spread and the people that they have encouraged to join terrorist organisations," said Dean Haydon, head of London police's Counter Terrorism Command.
Prosecutors said that in postings on social media, Choudary and his close associate Mizanur Rahman, 33, had pledged allegiance to the "caliphate" declared by Abu Bakr al-Baghdadi and said Muslims had a duty to obey or provide support to him.
Both men, who had denied the terrorism charges and claimed the case was politically motivated, were found guilty last month but their convictions could not be reported until Tuesday for legal reasons. They are due to be sentenced in September and could face a jail sentence of up to 10 years each.
Choudary, the former head of the now banned organization al-Muhajiroun, became infamous for praising the men responsible for the 9/11 attacks on the United States and saying he wanted to convert Buckingham Palace into a mosque.
Despite his often controversial comments and refusal to condemn attacks by Islamists such as the London 2005 bombings, Choudary has always denied any involvement in militant activity and had never been previously charged with any terrorism offence.
Rahman served two years in jail for encouraging followers to kill British and American troops in Afghanistan and Iraq during a protest in 2006.