Sen. John McCain, R-Ariz., makes the dubious claim that Sept. 11 hijackers entered the United States through Canada -- just days after Homeland Security Secretary Janet Napolitano came under fire for saying the same thing.

Napolitano retracted her claim on Thursday after Canadian officials chided her for the remark, calling it an unfortunate misconception. Napolitano admitted Thursday that she made a mistake -- since the 9/11 Commission concluded that the hijackers entered the U.S. from overseas.

But when asked about the gaffe on FOX News Friday, McCain said: "Well, some of the 9/11 hijackers did come through Canada, as you know."

This drew an instant retort from the Canadian embassy, which re-issued Canadian Ambassador Michael Wilson's public comments from Tuesday, in which he said:

"Unfortunately, misconceptions arise on something as fundamental as where the 9/11 terrorists came from. As the 9/11 Commission reported in July 2004, all of the 9/11 terrorists arrived in the U.S. from outside North America. They flew to major U.S. airports. They entered the U.S. with documents issued to them by the U.S. government. No 9/11 terrorists came from Canada."