Toronto, Oct 20 (IANS) Canada has once again rebutted the charges by American politicians that 9/11 hijackers entered the US from its northern neighbour.

The rebuttal came after US Republican Senate candidate Sharron Angle last week said that her country's "most porous'' border with Canada was a cause for concern.

"What we know is that our northern border is where the terrorists came through. That's the most porous border that we have,'' said Angle who is pitted against Senate majority leader Harry Reid in a very close race in Nevada.

Responding to the charges Monday, Canadian Ambassador Gary Doer said these were baseless.

Writing to the US Senate candidate, Doer said, "None of the 9/11 hijackers entered the United States from or through Canada.''

He said there have been no terrorist attacks on the US from Canada.

"Extensive investigations by US law enforcement authorities have established that all the hijackers entered the United States directly from third countries - not Canada - with visas issued by American diplomatic missions overseas,'' the envoy said.

Citing the 2004 report of the 9/11 Commission and the 2007 report on Canada-US Relations, the Canadian ambassador said, "Both confirmed that none of the 19 September 11 hijackers entered (the United States) by Canada.''

He told the US leader that "far from being a threat, Canada is a major contributor to economic prosperity in your state (Nevada). More than 1.3 million visitors from Canada visited Nevada in 2009, creating tens of thousands of jobs.''

Despite Canada's clarifications and denials in the past, a large number of Americans, including some leaders, still continue to believe that 9/11 hijackers came from Canada.

Early last year, US homeland security secretary Janet Napolitano ruffled Canadians when she said that "to the extent that terrorists have come into our country or suspected or known terrorists have entered our country across a border, it's been across the Canadian border. There are real issues there."

When she was specifically asked about 9/11 hijackers, she said, "Not just those but others as well."

Defending her charges, former US presidential candidate John McCain too had said that "some of the 9/11 hijackers did come through Canada, as you know.''

American fears have been heightened by the unearthing of a couple of major terror plots in Canada since 2006 and arrests of many radicalized Muslim youths.

Canada is home to more than a million Muslims, and their population is estimated to triple in the next two decades.