An American expert in violent self-defence has been excluded from entering the UK by the Home Office.
Tim Larkin tried to board a plane from his home in Las Vegas on Tuesday, but was given a UK Border Agency letter saying "his presence here was not conducive to the public good".
Mr Larkin, who was due to host seminars, told the BBC the move was a "gross over-reaction".
The Home Office said he was subject to an exclusion order.
A spokeswoman said: "The home secretary will seek to exclude an individual if she considers that his or her presence in the UK is not conducive to the public good."
Mr Larkin - who trained as a US Navy Seal - runs a company teaching combat to military and law enforcement clients in the United States.
'Black swan occasions'
He teaches self-defence techniques, which according to his own website, are designed to inflict "crippling pain" to an attacker, and claims violence is "your ultimate survival tool".
Mr Larkin had been invited to be a keynote speaker at The Martial Arts Show conference in Birmingham on 12 and 13 May, and to hold a seminar in Tottenham.
Both areas were targeted by rioters last August.
Mr Larkin told BBC Radio 4 he believed he was being excluded for criticising Britain's self-defence laws.
"I am not advocating that the UK should be like the US. What I am advocating is that the UK should go back to laws it had, prior to 1920."
But Mr Larkin insisted there was "nothing outrageous" about his views, and his intention in visiting the UK, was not to incite "violence".
"This is not being a vigilante. You are sitting in your house and you're being attacked, or you're attacked out in the street... There's an awful lot of martial arts and self defence being taught there right now that gives no instruction on [how to hurt] the human body.
He continued: "There are those rare, rare black swan occasions - like the riots - where law-abiding citizens are put in situations where they are facing grievous bodily harm and they hesitate because they are afraid of being prosecuted. That is a very real thing."
Mr Larkin claims he has a lot of support in the UK, and he says he may appeal to MPs.
A visit in 2009 to Slough, in Berkshire, where Mr Larkin held a class intended to teach how to "maim and kill in self-defence", provoked widespread condemnation from the community.
He has previously told the BBC that his training leads clients to become less violent.
"The more you know about lethal applications to the body, the less violent you are. You don't go out seeking it, and you certainly wouldn't misuse the tool."