By Daniel Lovering

BOSTON (Reuters) - A Massachusetts man convicted of supporting al Qaeda was sentenced to more than 17 years in prison at a court appearance on Thursday in which he shouted "You're a liar!" at the prosecutor.

Tarek Mehanna, 29, was found guilty in December on all seven charges against him, including "providing material support to terrorists," conspiracy to kill in a foreign country and lying to law enforcement officers.

But Mehanna, a U.S. citizen from Sudbury, a Boston suburb, maintained his innocence at his sentencing in U.S. District Court in Boston on Thursday, telling the judge he "never plotted to kill Americans at shopping malls or anywhere else."

Judge George O'Toole said he was troubled by Mehanna's lack of remorse and sentenced him to 17-and-a-half years behind bars followed by seven years of supervised release. The maximum penalty for his charges was life in prison.

Defense attorney J.W. Carney Jr. said he would file an appeal.

While Mehanna was in many ways an exemplary citizen, the judge said, "he became consumed with a religious enthusiasm" that included a horrifying aspect. "The horrifying part came to dominance," O'Toole said.

Prosecutors said Mehanna, who holds a doctorate from the Massachusetts College of Pharmacy and Health Sciences, answered a call to action from Osama bin Laden to fight U.S. soldiers.

They said he traveled to Yemen in 2004 to seek terrorism training, but never received it, and planned to travel to Iraq to fight U.S. troops. They also accused him of translating videos and texts from Arabic to English and distributing them on the Internet to further al Qaeda's cause.

But defense attorneys argued that Mehanna was "a typical American kid" trying to learn about his Muslim heritage by studying Islamic law and translating classical texts. He traveled to Yemen to visit schools where he hoped to study, they said.

Mehanna openly opposed the U.S. military presence in Iraq and showed admiration for bin Laden's efforts to expel foreign powers from Muslim countries, defense attorneys said. But he never worked for al Qaeda, nor had direct contact with the group, they said.

At his sentencing, Mehanna, wearing an orange prison uniform, spoke defiantly about his arrest by FBI agents four years ago, saying he had rejected their offer to choose the "easy way" and become an informant rather than facing prosecution.

He said he learned from comic books as a child that there were oppressors and oppressed people in the world, and in school developed an admiration for Native Americans and civil rights leaders including Malcolm X.

Declaring himself "a very proud Muslim," he blamed sanctions against Iraq for the deaths of thousands of children and said Muslims should defend themselves against foreign invaders.

"This is not extremism," said Mehanna.

Federal prosecutor Aloke Chakravarty told the judge FBI agents said some of Mahenna's statements were false.

"You're a liar!" Mehanna shouted at the prosecutor.

As he was escorted out of the courtroom in handcuffs, Mehanna kissed the air toward family and friends, who clapped and shouted, "We love you, Tarek!"

(Editing By Barbara Goldberg and Mohammad Zargham)