Anthony Small, a former British boxing champion, was arrested by the counter-terrorism unit for trying to assist two ISIS recruits flee to Syria hidden in a truck.
The two ISIS recruits, reportedly banned by the British authorities from flying out of Britain, planned to sneak out of Dover in a truck, to eventually reach Syria and join the Islamic State.
The 33-year old former boxing champion is a Muslim convert who is open about his support of Islamic hate preacher Anjem Choudary and the ISIS jihadi activities.
The Daily Mail report noted that the counter-terrorism sleuths had proof linking the former boxing champion with the plot to sneak the two ISIS jihadists out of Britain. The investigators say that several underground networks are operating in the UK that help Islamist jihadists to escape to Syria.
The two ISIS recruits were discovered on Sunday by the authorities in a lorry along with a dozen migrants and an Eastern European accused of acting as a fixer.
The counter-terrorism investigators found that Small was also involved in the jihadi operations. The former boxing champion was arrested along with another man, aged 40, from their homes in South East London.
Small, who gave up boxing claiming that it was a 'sinful' life, has been charged with 'preparing acts of terrorism.'
Soon after Small's arrest, Choudary posted a Twitter message calling on Allah to protect Abdul Haqq, the Muslim adopted name of Small, and 'all Muslims kept as hostages by the oppressive British regime.'
May Allah (SWT) protect Br. Abdul Haq & all Muslims being kept hostage by the oppressive British regime & its police! http://t.co/tbSxCrtXNX
— Anjem Choudary (@anjemchoudary) December 4, 2014
In September, Choudary and nine others were arrested and their passports confiscated by the British authorities to stop them from leaving the country. However, one of those arrested, Siddhartha Dhar, 31, was able to escape UK and reach Syria in November. He then had posted a photo of himself online holding an AK-47 rifle and his newborn baby.
Small has held both British and Commonwealth light middleweight titles and turned professional in his early 20s under the alias Sugar Ray Clay Jones Jr. He converted to Islam at 24.
In recent months Small has posted a series of inflammatory videos online. In one such video uploaded on YouTube, Small described the US as the "United Snakes of America" and called American journalist James Foley as "Mr Beheaded infidel".
He said: "We have to be objective and non-biased, that the beheading of James Foley, Mr Beheaded infidel, not to be disrespectful to him or his family, I can't remember his name, Mr Infidel, it wasn't unprovoked."
Small also warned of future attacks if the UK took military action against ISIS.
"If Britain ups its attacks, I won't be considering going near any buses, trains or tubes," he said.