OTTAWA - American right-winger Ann Coulter's speech at the University of Ottawa was scrubbed Tuesday night after organizers said security could not guarantee her safety from protesters outside.

A spokesman for the organizers said about 2,000 "threatening" student protesters pressed up against the doors and security advised she not appear.

"It would be physically dangerous for Anne Coulter to proceed with this event," said Conservative activist Ezra Levant.

"This is an embarrassing day for the University of Ottawa and their student body ... who chose to silence her through threats and intimidation."

The announcement was greeted with shouts of "Shame" and "We want Ann" from about 100 who had managed to get into the hall.

But even before the protesters arrived, there was sign of trouble. A crush of bodies greeted organizers about 90 minutes before Coulter's 8:15 p.m. speaking time as about 1,000 showed up for the 400-seat hall.

At about 7:30 a fire alarm was triggered.

Then hundreds of protesters arrived, mostly students carrying signs and chanting. There was no accurate head account, but one student said the protesters accounted for about several hundred.

"Ann Coulter should go back to where she came from because we don't want her back here," shouted Ellen Ocran, a University of Ottawa student in a shouting match with a Coulter backer.

A protest organizer, international studies student Mike Fancie, said he was happy they were able to stop Coulter from speaking.

"What Ann Coulter is practising is not free speech, it's hate speech," he said. "She's targeted the Jews, she's targeted the Muslims, she's targeted Canadians, homosexuals, women, almost everybody you could image."

Levant blamed the cancellation on university academic vice-president Francois Houle, who had written Coulter to warn her that Canadian laws make provisions for hate speech.

"Promoting hatred against any identifiable group would not only be considered inappropriate, but could in fact lead to criminal charges," he warned her in the letter, which Coulter quickly leaked to the media.

The university has refused to comment since, but Levant said Houle's not-too-subtle advice to Coulter emboldened students to block her appearance.

Coulter was in the middle of a three-city tour of Canada which began at the University of Western Ontario in London on Monday, and ends in Calgary on Thursday.

The event in London went without incident, but not without controversy.

When answering questions from students, Coulter told a 17-year-old Muslim student to "take a camel" instead of a the flying carpet she has previously suggested Muslims use for transportation.

If publicity was the goal of Coulter's Canadian tour, the trip has already been a smashing success.

She even got a mention in the House of Commons, with New Democrat MP Olivia Chow accusing the government of hypocrisy in allowing her into the country, after having given the boot to an ideological opposite.

Chow said the decision last year to bar British MP George Galloway, who has expressed pro-Palestinian views, shows the Conservatives have a double-standard on freedom of speech.

Immigration Minister Jason Kenney defended keeping Galloway out of the country by noting his financial help to a terrorist group, Hamas.

"Hogwash," responded Chow.

"George Galloway has no criminal record. He can travel the United States, all over the world. What the minister is doing ... people he agrees with, fine come; people he doesn't agree with, you can't come."

Coulter is a best-selling author and syndicated columnist who has been called one of the leaders of the angry right wing in the United States, along with talk show hosts Rush Limbaugh and Glen Beck. She embraces the outrage she triggers although she has often dismissed the ensuing controversy by suggesting she was trying to be humorous.

Asked to comment on the Harper Conservatives, Coulter said she didn't pay much attention to Canadian politics, but judged they were not her cup of tea.

"If they support same-sex marriage and socialized medicine, no they are not conservative enough," she said.

And she summed up the harsh reaction to her with another smile.

"I am dangerous," she said.