The National Post reports in its Tuesday edition that unnamed sources say American officials have taken the "highly unusual" step of rejecting Canada's bid to take part in senior-level North American free-trade agreement talks between the United States and Mexico later this week. The Post's Tom Blackwell writes that one source says attempts by Foreign Affairs Minister Chrystia Freeland to get a seat at the table in Washington Thursday were either ignored, or spurned outright by the office of U.S. Trade Representative Robert Lighthizer. Another source says the request to be at the meeting was made in a low-key fashion "so as not to spark a diplomatic incident" and was followed by "a retreat to diplomatic silence." Mr. Lighthizer is slated to meet Economy Minister Ildefonso Guajardo of Mexico after similar bilateral meetings between the officials last week made significant progress, analysts say. Canada's apparent sidelining follows Mr. Lighthizer's recent comments that he hoped to strike a separate deal with Mexico, then use that as pressure to win compromises from Canada. "It is highly unusual ... for Canada not to participate in the new discussions," says Center for Canadian Studies head Chris Sands.