His planned Dec. 22 appearance at the Reviving the Islamic Spirit conference has been attacked by an anti-Islamism website and those complaints have been picked up by some mainstream media outlets.
The critics have raised concerns about radical views and the alleged affiliation of other speakers at the event later this month; they have also pointed to alleged ties between major conference sponsors and the Islamic militant group Hamas.
But Trudeau makes no apologies for his decision to attend.
When asked about the controversy, Trudeau said he doesn't share the critics' concerns and he accuses them of trafficking in misinformation. He said politicians from all parties have spoken at the annual Toronto event — including former New Democrat leader Jack Layton a few years ago.
"If there are concerns about some of the speakers that I've heard rumours about, I think there's also a bit of misinformation," the Liberal leadership candidate said during a news conference Monday in St-Jerome, Que.
"I've heard a number of people express concerns about this event that I certainly don't understand and I don't share...
"It's a group of young people who've pulled this together. Most of the organizers are young Muslims who are looking at trying to bridge the gap between the reality for Muslim Canadians and mainstream Canada and I'm very proud to be able to contribute."
The convention had 30,000 attendees in 2011 and at least 20,000 are expected this year. The working title of Trudeau's speech is: "Being Inclusive in Canada: Our Story, Our Politics, Our Future."
A spokeswoman for the convention said the criticism is an example of broader fear-mongering about Muslims.
"Unfortunately, (such criticism) will always exist and I think the idea of a large congregation of Muslims gathering is often attached with speculation over the last decade or so," Farhia Ahmed said Tuesday.
"There's been wide speculation about whether or not Muslims are all terrorists... That's also what the media has been portraying."
She said the allegations about malicious activities linked to event speakers and sponsors have not been proven: "From the opinion of the organizing committee, most of it is fear-mongering," Ahmed said.
The event, founded by young Canadian Muslims a decade ago, aims to promote a forum for people to hear different viewpoints related to Islam.
Ahmed said the organizers do not condone any negative behaviour, activities or anything related to terrorism. She could not immediately say whether any potential presenters had been turned away in the past for these concerns.
"Absolutely we would turn them down and have no relation with them," she said.
Ahmed added that many politicians have participated in past conventions.
She said Prime Minister Stephen Harper had sent a letter of support and congratulations to coincide with last year's event, which was the organization's 10th anniversary. She said the message was read aloud by a government representative.
Trudeau is just one of many politicians who have received invitations, Ahmed added.
Criticism of Trudeau's appearance emerged on the website Point de Bascule Canada (or Tipping Point Canada), and the theme was picked up by a pair of popular radio stations in Montreal, one French and one English, and on the Sun News TV network.
Point de Bascule Canada calls itself an independent, non-partisan website that "defends our liberties by educating people on the Islamist threat."
The website did not immediately respond to an interview request.
But an article it posted alleges that three people scheduled to address this year's convention "have supported Hamas in the past and promoted an Islamic conquest of the West." Since 2002, the federal government has considered Hamas a terrorist organization and it is banned in Canada.
Among other examples, Point de Bascule Canada provides a link to a 2011 Toronto Star story that says one charity, listed as an event sponsor, had its status revoked by the Canada Revenue Agency for allegedly using "deceptive fundraising" to send nearly $15 million in donations to Hamas.
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