TORONTO - An association representing university teachers is appealing to Prime Minister Stephen Harper to allow Williams Ayers into Canada.
Ayers, a former U.S. radical whose name arose in Barack Obama's presidential election campaign, was barred from Canada on Sunday.
The education professor in Chicago at the University of Illinois was supposed to give a speech Monday night at the University of Toronto.
Ayers said he doesn't know why he was barred, adding he "couldn't possibly be a threat to Canada."
In an open letter to Harper, the Canadian Association of University Teachers says "it is wrong for the government of Canada to decide which scholars universities can invite to their campuses."
The association is calling for a public investigation into Ayers' denial of entry into Canada.
The Illinois professor was detained at Toronto's Pearson International 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.
Ayers had planned to speak about educational reform and the importance of Obama's inauguration on Tuesday.
