LONDON -- An American self-defense expert -- who teaches people how to deal with "kill-or-be-killed" situations -- has been banned from entering Britain. Officials say Tim Larkin's presence "was not conducive to the public good."

Larkin attempted to board a flight to the U.K. from Las Vegas, but was given a letter from the U.K. Border Agency saying he would not be allowed in, according to BBC News.

"The home secretary [the U.K. government's interior minister] will seek to exclude an individual if she considers that his or her presence in the U.K. is not conducive to the public good," a government spokesperson told the BBC, confirming Larkin was subject to an exclusion order.

Heathrow chaos: Travelers spend more time in line than in the air

Larkin, who runs a company called Target Focus Training, previously came to the U.K. in 2009, when he taught a class to teach people how to "maim and kill in self-defense," the BBC reported.

Trains Navy SEALs
According to his firm's website, Larkin is "the guy operations like the US Navy SEALs, Army Special Forces and the U.S. Border Patrol call in behind-the-scenes to teach them when it’s 'kill-or-be-killed.' The truth is … your best self defense in a life-or-death confrontation is injuring the other guy. And it’s the one thing that makes us so different."

Larkin has spoken to government officials and business people in more 40 countries about surviving life-or-death violence, according to the website. He also co-authored a book called How To Survive The Most Critical 5 Seconds Of Your Life and writes an online newsletter, Secrets For Staying Alive When Rules Don’t Apply.

The U.K.'s Guardian newspaper ran an online poll about the decision to prevent Larkin from coming to Britain. At 10:15 a.m. ET, more than 72 percent of those choosing to vote said he should have not have been banned.

The BBC said Larkin had been invited to speak at "The Martial Arts Show" conference in Birmingham on May 12 and 13, and to hold a seminar in the Tottenham area of London. Both places experienced rioting during widespread disorder in the U.K. in August last year.

Riots break out in London after fatal-shooting protest

Larkin told the BBC that he thought he had been banned for arguing that U.K. law should be changed to allow people to defend themselves without fear of criminal charges being brought against them.

"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-defense being taught there right now that gives no instruction on [how to hurt] the human body," he said.

The science of the London riots

"There are those rare, rare black swan occasions -- like the [August] 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," he added.

More world news from msnbc.com and NBC News:

• Video: Would-be al-Qaida bomber was double agent
• Study: Plastic in 'Great Pacific Garbage Patch' increases 100-fold
• US charity's gift to UK troops: $2 million for 'sanctuary'
• $868K mystery: Nigeria stock exchange's yacht, Rolexes vanish
• UK jails 9 members of sex gang who 'shared' teen girls
• Heathrow chaos: Travelers spend longer in line than on jets
• Leak hits Shell Nigeria pipeline at center of environmental case
• Poll: Most Egyptians think US aid billions have 'negative effect'

Follow us on Twitter: @msnbc_world