ISIS is plotting a new wave of terrorist attacks across the UK by using ‘crocodile cells’ consisting of sleeper agents hiding in plain sight in western Europe, an expert has warned.

The alert comes after it was revealed that Abdul Lathief Jameel Mohamed, one of the ring-leaders of the Sri Lanka church bombings, which resulted in the deaths of more than 250 churchgoers on Easter Sunday, was studying at Kingston University in south-east London between 2006 and 2007.

During this time a hate preacher with links to the death of Lee Rigby gave a speech encouraging Jihad.

MI5 is urging churches and mosques in Britain to have counter-terrorism training amid concerns of more Islamic terror attacks.

Charlie Winter, of the International Centre for the Study of Radicalisation at King's College London, told MailOnline:

‘Now that Isis has been defeated in Syria and Iraq, it will become more violent outside this area. It's a grim outlook, but we are likely to see more attempts at attacks, more regularly, for the foreseeable future. Sri Lanka was not a one-off. If anything, it was a test run.’

UK counter-terrorism investigators are trying to establish links with extremist organisations during his time in Britain.