With U.S. mid-term elections approaching, conservatives south of the border have begun to rail against Canada as a transit route for terrorists, prompting Canada's ambassador in Washington to wade into the fray.

The debacle began when Sharron Angle, a Tea party candidate from Nevada who is running for a seat in the U.S. Senate, suggested to a group of Hispanic youths that the 9/11 bombers entered the U.S. from Canada.

"What we know is that our northern border is where the terrorists came through," she said, in remarks captured on video. "That's the most porous border that we have. We cannot allow terrorists; we cannot allow anyone to come across our border if we don't know why they're coming."

None of the 9/11 terrorists entered the U.S. from Canada.

Angle, who is in a close race Senate majority leader Harry Reid, was trying to deflect criticism of television ads for her campaign that focus on illegal immigration. Although they mention Mexico and feature dark-skinned teens, she said the ads weren't necessarily aimed at Hispanics.

Her remarks led Canada's ambassador in Washington, Gary Doer, to write a letter to Angle's campaign on Monday.

"There have been no terrorist attacks on the United States coming from Canada," he wrote, referencing the 9/11 Commission report. "I can assure you that Canada takes border security very seriously and trust you will see fit to set the record straight."

"We do not have a 'porous' border but rather one of the more secure borders in the world," he added.

On Tuesday, Angle's campaign responded by focusing on the case of Ahmed Ressam, an Algerian man who was apprehended by American authorities in 1999 while trying to enter the U.S. near Victoria. He was subsequently convicted of plotting to bomb Los Angeles International Airport.

Conservative pundit Michelle Malkin has defended Angle for making the comments.

"Angle is absolutely spot-on about the porous northern border," Malkin wrote in a blog post on Tuesday. "She's saying what homeland security officials have been saying for years."

She then listed a number of terrorist suspects linked to Canada, according to Janice Kephart, a lawyer who worked for the 9/11 Commission. However, none of those named are tied to the Sept. 11, attacks.

"It's important to let people know that we care about security and we care about factual errors being made," Doer told reporters. "And when somebody goes off the facts, we're going to speak up."

Doer isn't the first Canadian ambassador to weigh in on the issue. In 2009, former ambassador Michael Wilson corrected Homeland Security czar Janet Napolitano after she suggested there was a Canadian connection to the 9/11 terrorists.

However, U.S. officials have expressed fears of terrorists successfully entering the country from Canada.

In 2008, Michael Chertoff, who was then secretary of homeland security, told the New York Daily News that more than a dozen terrorist suspects had attempted to enter the U.S. from Canada.

With a report from CTV's Washington Bureau Chief Paul Workman and files from The Canadian Press