An animal rights activist barred from Britain is considering legal action against the government and will address a conference in Kent by video link.
Animal testing remains a contentious issue
US trauma surgeon Dr Jerry Vlasak was barred after reportedly saying millions of animal lives could be saved if a handful of vivisectionists were killed.
Home Secretary David Blunkett wrote to him earlier this week saying he and his wife would not be allowed into Britain.
Dr Vlasak will give the keynote speech at the conference live from the US.
A Home Office spokeswoman said Dr Vlasak and his wife Pamela were being excluded on the grounds that their presence in Britain "would not be conducive to the public good".
Dr Vlasak said he had been on contact with his lawyers about taking legal action against the government.
"I'm disappointed, as you might expect," he added.
Campaigners are protesting against practices at Huntingdon Life Sciences
"Britain has a long history of providing refuge for people with their own ideas.
"They have not really said how long I am banned from the country - whether I was just banned from the one particular conference - whether I am barred for life or maybe the life of Mr Blunkett."
It was also "unfair" to ban his wife, Dr Vlasak said.
"She had not planned to speak at the conference - she was on holiday.
"She has become collateral damage.
"The home secretary listed minor infractions - but nothing illegal.
"He said she advocated civil disobedience."
Dr Vlasak, himself a "former animal experimenter", told BBC Radio Kent Mr Blunkett said he was a "threat to the public good".
But the only threat he posed was to a pharmaceutical industry "looking for a billion dollar loss this year due to the actions of animal rights protesters".
"They have made their wishes known and the Home Office has kept me away for those reasons."
Dr Vlasak said he had been "misrepresented" in a newspaper interview in which he appeared to advocate assassinations.
But he added: "Violence is used so readily against animals. There is moral justification if animal rights campaigners use violence to defend themselves and animals."
He had been asked to speak on the "scientific invalidity" of killing animals in laboratories, Dr Vlasak added.
The three-day Animal Rights Conference 2004 in Tonbridge is being organised by anti-vivisection groups Speak and Stop Huntingdon Animal Cruelty.
They have been campaigning against practices at the Cambridgeshire research centre Huntingdon Life Sciences.
The gathering will include tips on working undercover, classes on self-defence and unarmed combat and hunt saboteurs' actions.
It comes after the Home Office unveiled plans last month for a crackdown on animal rights campaigners who use terror tactics against scientists.
This followed concern the economy was being harmed by the security costs firms face in dealing with such activism.