An American animal rights activist could be banned from Britain for reportedly advocating the killing of scientists involved in animal research, the home secretary said yesterday.

Jerry Vlasak, a paid scientific adviser to the group spearheading the campaign to stop the construction of a new research laboratory at Oxford University, allegedly said that assassinating vivisectionists could save the lives of millions of animals, according to the Observer newspaper.

The home secretary warned that Mr Vlasak could be treated in the same way as someone advocating the murder of people because of their colour or religion.

"I am asking that we examine the authenticity of the claims in those quotes, the attitude of this individual and whether his presence would be non-conducive to the public good, and it is," Mr Blunkett told BBC1's Breakfast with Frost programme. "If we have to [kick him out], that is what we will do."

Mr Vlasak allegedly told the Observer: "I think violence is part of the struggle against oppression. If something bad happens to these people [animal researchers], it will discourage others. It is inevitable that violence will be used in the struggle and that it will be effective."

The newspaper also said that Mr Vlasak stood by his claim, at an animal rights convention in Washington, that "I don't think you'd have to kill - assassinate - too many [scientific researchers] ... I think for five lives, 10 lives, 15 human lives, we could save a million, 2 million, 10 million non-human lives".

However, Mr Vlasak, who is a heart surgeon in Los Angeles, told the Guardian yesterday that he had been quoted out of context and was planning to consult an attorney. Describing the story as "total rubbish", he said: "I am not suggesting anybody kill any other human being, but I am saying that historically violence has been used on both sides in struggles like these. If you look at other historical movements that seek to end grievous violence perpetrated on innocent victims - including fights such as that against apartheid in South Africa or against black slavery in the US - violence has always been used as an arsenal in those struggles and I do not think the animal rights liberation movement is any different. It is unfortunate, but it is true. I am not advocating the killing of anybody - any human or non-human."

He also had harsh words for Mr Blunkett: "I find it curious that your home secretary would threaten to ban a physician from entering the country based on a newspaper headline. I think if David Blunkett has any concerns about my right to free speech he should call me and ask me personally, or talk to me personally or correspond with me personally, and not believe a sensationalist newspaper story."

A spokesman for Speak, the group leading the campaign against the building of a new research laboratory at Oxford University, said Mr Vlasak was employed as a scientific adviser, drawing on his expertise as a former vivisectionist.

Building work on the Oxford laboratory was halted last week when Montpellier, the main contractor, pulled out of the project after shares in the company fell by 19% after the publication of a letter - purporting to be from the group's chairman - that urged shareholders to sell their stock to avoid reprisals from the animal rights movement.