One of the Sri Lankan suicide bombers was allegedly radicalised by hate preacher Anjem Choudary.
Abdul Lathief Jameel Mohamed, 37, was the link between Islamic State and the bombers, according to security services.
Abdul Lathief Jameel Mohamed (pictured as a school boy)
A security official told the BBC: 'He was completely radicalised and supported the extremist ideology. I tried to reason with him.
'When I asked him how he got into this… he said that he attended the sermons of the radical British preacher Anjem Choudary in London. He said he met him during the sermons.'
Choudary is considered one of the UK's most notorious hate preachers.
The father of five spent three years of a five-and-a-half year sentence in prison after he was detained in 2016 under terror laws for his encouragement to Muslims to join Isis.
The Choudary-led extremist group al-Muhajiroun was outlawed by the Government following the 2005 7/7 attacks on London but it has continued to operate under a number of different images.
He helped radicalise some of Britain's most notorious terrorists, including London Bridge terror attacker ringleader Khuram Butt, and Michael Adebolajo and Michael Adebowale, who murdered Fusilier Lee Rigby in Woolwich, south-east London.
Mohamed tried to blow up the luxury Taj Samudra hotel in the Sri Lankan capital Colombo on Easter Sunday.
But he is believed to have botched his attempt to detonate his bomb at the five-star hotel and is thought to have blown himself up at a much smaller guest house.
UK counter-terrorism investigators believe he attended Kingston University in south-west London from 2006-07, before then studying for a postgraduate degree in Melbourne, Australia.
In a previous interview with MailOnline his sister Samsul Hidaya said Abdul Lathief Jameel Mohamed had been educated to the highest level but became increasingly withdrawn and intense as he descended into extremism.
'My brother became deeply, deeply religious while he was in Australia,' she said. 'He was normal when he went to study in Britain, and normal when he came back.
'But after he did his postgraduate in Australia, he came back to Sri Lanka a different man.
'He had a long beard and had lost his sense of humour. He became serious and withdrawn and would not even smile at anyone he didn't know, let alone laugh.'
DailyMail UK (dailymail.co.uk)