One of Britain’s most notorious Islamist preachers, Anjem Choudary has been found guilty of inviting support for the Islamic State group. The verdict was handed down Tuesday in London’s court, according to Huffington Post. He was convicted of using online lectures and messages to motivate people to support the banned group that has substantial power in Syria and Iraq.

Prosecutors accused Choudary and his close associate Mizanur Rahman for using social media to pledge their allegiance to the “caliphate” declared by Abu Bakr al-Baghdadi, according to the Guardian. They also told their followers they had to obey the ISIS leader and travel to Syria to support him.

Despite their encouragement to the Muslim community, the men are denying the terrorism charges against them and claim the case was politically motivated. Although they were found guilty in July, their convictions could not be reported until Aug. 16 for legal reasons.

Choundary initially became infamous when he praised the men who carried out the 9/11 attacks and suggested Buckingham Palace be turned into a mosque, but since then his notoriety has grown. He made regular appearances on television whenever attacks by Islamist militants took place and in turn blamed Western foreign policy for targeting Muslims. He also used his time in the spotlight to inspire the youth to turn carry out terrorism in Britain and Europe.

“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 organizations,” Commander Dean Haydon, the head of Scotland Yard’s counter-terrorism command, told the media.

Although Choundary makes contentious comments and has never denounced the terrorist acts carried out by various Islamists, he has always denied any involvement in attacks and has never been charged with anything tied to terrorism with the exception of his most recent conviction.

Choudary and Mizanur Rahman are expected to be sentenced next month and each face up to 10 years in prison.