Gold Star father Khizr Khan has canceled a scheduled speech in Toronto after being told his "travel privileges are being reviewed," according to the event organizer.
It was not immediately clear which government agency contacted him or what was under review. Khan has lived in the U.S. since 1980 and is a naturalized U.S. citizen.
He was scheduled to speak Tuesday at a luncheon hosted by the Toronto-based organization Ramsay Talks.
The two-hour event was slated to include a presentation and question-and-answer session on "what we can do about the appalling turn of events in Washington -- so that we don’t all end up sacrificing everything," according to the organizer.
In a statement posted on Facebook, Khan said he was not told why his travel status was under review.
"This turn of events is not just of deep concern to me but to all my fellow Americans who cherish our freedom to travel abroad," he said, according to the statement. "I have not been given any reason as to why. I am grateful for your support and look forward to visiting Toronto in the near future."
Khan, whose family is Muslim, made national headlines after his fiery speech at the Democratic National Convention, during which he blasted Donald Trump's rigid stance on Muslim immigration.
"Donald Trump, you're asking Americans to trust you with their future. Let me ask you, have you even read the United States Constitution?" Khan said before pulling a pocket Constitution from his jacket. "I will gladly lend you my copy. In this document, look for the words 'liberty' and 'equal protection of law.'"
Khan immigrated to the U.S. from Pakistan in 1980. He and his wife, Ghazala, became American citizens six years later.
Their son Humayun Khan was killed by a suicide bomber in Iraq in 2004. The Army captain was running toward a taxi cab approaching his troops when a bomb inside exploded. Khan was killed while the other soldiers remained safe.
Khan received the Purple Heart and the Bronze Star posthumously.