WASHINGTON—The Canadian government is yet again trying to set the record straight about 9/11 hijackers and where they didn’t come from.

Ambassador Gary Doer has written to Republican Senate candidate Sharron Angle, who last week referred to the U.S.-Canadian border as “the most porous border” the country has.

Angle, a tea party-backed candidate running a close race in Nevada against Senate Majority Leader Harry Reid, said “what we know is our northern border is where the terrorists came through.”

In his note to Angle on Monday, Doer emphasized that “none of the 9/11 hijackers entered the United States from or through Canada.”

He said extensive investigations by U.S. law enforcement authorities have established that all of the hijackers entered the U.S. directly from third countries – not Canada – with visas issued by U.S. diplomats.

This is not the first time Ottawa has had to inform U.S. politicians that their perception of Canada’s involvement in the 9/11 terrorist attacks is wrong.

In April, 2009, Homeland Security Secretary Janet Napolitano raised eyebrows when she stated the oft-repeated myth as a fact.

She later insisted she knew there was no Canadian connection to 9/11, but within days Arizona Senator John McCain, the 2008 Republican presidential candidate, repeated the claim.

Republican Newt Gingrich also had to apologize to the Canadian ambassador in 2005 for making the same claim.

Doer reminded Angle that far from being a threat, Canada is a major contributor to the prosperity in her state, with more than 1.3 million Canadians visiting Nevada in 2009, creating tens of thousands of jobs. The trade between Canada and Nevada in the same year totalled more than $1.3 billion.

“I can assure you that Canada takes border security very seriously and trust you will see fit to set the record straight,” Doer ended the letter, which was posted on the website of the Department of Foreign Affairs.