TORONTO - William Ayers, a former U.S. radical who featured prominently in Republican efforts to thwart Barack Obama's election campaign, doesn't know why he has been barred from Canada.
  
Ayers, who is an education professor in Chicago at the University of Illinois, was supposed to give a speech Monday night at the University of Toronto.

"I got off the plane like everyone else and I was asked to come over to the other side," Ayers told the Toronto Star in an interview from Chicago. "The border guards reviewed some stuff and said I wasn't going to be allowed into Canada."

Ayers added that he "couldn't possibly be a threat to Canada."

His lawyer Paul Copeland told The Canadian Press he has seldom spent a more frustrating time than that trying unsuccessfully to persuade Canadian border officials to reverse a decision to bar his client from entry at the Toronto City Centre Airport Sunday night.

Ayers was not allowed to meet with his lawyer, Copeland said.

Anna Pape, a spokeswoman for the Canada Border Services Agency, said "there is no right to counsel" in such cases.

She said only if a person is detained by the agency are they advised of their rights, including the right to counsel.

But Copeland did not agree with the agency's "interpretation of the legislation."
  
"They wouldn't let me speak to any of the decision-makers and they wouldn't let me speak to him."

Copeland said the border officials could have let Ayers in under a temporary resident's permit but they declined. Pape said all decisions are at the discretion of the officials on hand at the time.

The Illinois professor was at the airport for at least 3 1/2 hours, while he and border officials wrangled over his fate.

Ayers was mentioned often during the U.S. presidential campaign, cited by former Republican vice-presidential hopeful Sarah Palin as proof Obama had links to terrorism.

A news release by the university said the centre was surprised Ayers, a distinguished professor, community organizer and author, would be deemed a threat by Canadian border security.

Jeffrey Kugler, executive director of the university's Centre for Urban Schooling, called the refusal to allow Ayers into the country a violation of academic freedom.

Ayers had planned to speak about educational reform and the importance of Obama's inauguration Tuesday.

The university said Ayers, who also once sat on the board of a charitable foundation alongside Obama, was refused entry because of a 1969 conviction during an anti-war demonstration.

The academic and former 1960s radical was a co-founder of the Weather Underground, a group that planted bombs on U.S. government property, including the Capitol and the Pentagon. Three group members died when a bomb they were making went off.

Ayers went into hiding and resurfaced a decade later. The charges against him were eventually dropped and he went on to rebuild his life as an author and lecturer.

Ayers has told the Star he has been to Canada many times before for speaking engagements in Toronto, Ottawa and Vancouver.

But he has also been denied entry into Canada before too, when he was supposed to give a lecture at the University of Calgary in July 2005.

The Star reported Tuesday that Olivia Chow, the NDP immigration critic plans to write Immigration Minister Jason Kenney and request that he grant Ayers permission to come to Toronto to give his lecture.