Maher Arar, 37, appeared before a joint hearing of House subcommittees by video, because he is still on a U.S. government watch list.
"Let me personally give you what our government has not: an apology," said Bill Delahunt, D-Mass., as he opened the hearing. "Let me apologize to you and the Canadian people for our government's role in a mistake."
Republican Dana Rohrabacher also apologized, but said he would fight any efforts by Democrats to end the practice of extraordinary rendition, whereby terror suspects are grabbed by government agents and taken to another country where local authorities may torture confessions out of them.
"Yes, we should be ashamed" of what happened in the case, Rohrabacher said. "That is no excuse to end a program which has protected the lives of hundreds of thousands if not millions of American lives."
Arar, a Syrian-born Canadian citizen, was detained by Homeland Security agents on Sept. 26, 2002, as he stopped over in New York's John F. Kennedy International Airport en route home from a vacation. Days later, he was sent by private jet to Syria where, according to Canadian officials, he was tortured.
The Canadian government has apologized to Arar for its role in the case, and agreed to pay him almost $10 million in compensation. The Bush administration has not apologized.
The administration has refused to say much about its extraordinary rendition program, other than it is an extremely important tool in combatting terrorists.
The hearing comes a day before Hollywood is to offer its own take on the contentious anti-terror program: "Rendition," starring Reese Witherspoon, opens in U.S. theaters Friday.