An American man is on trial in the northeastern state of Massachusetts on charges helping al-Qaida to promote holy war on the Internet.

Prosecutors opened their case in a Boston court Thursday, accusing 29-year-old Tarek Mehanna of answering a call for violent jihad from former al-Qaida leader Osama bin Laden.

They say Mehanna, a Muslim, translated terrorist documents from Arabic into English and distributed them online. One of the documents was an al-Qaida manual on ways to engage in jihad.

Prosecutors also accuse Mehanna of traveling to Yemen in 2004 in a failed effort to find terrorism training. Al-Qaida's Arabian Peninsula affiliate is based in Yemen's lawless regions.

Defense lawyers said the man from the town of Sudbury, near Boston, was exercising his free speech rights by disseminating texts about jihad on the Internet and criticizing the U.S.-led war in Iraq.

Mehanna has a doctorate from the Massachusetts College of Pharmacy and Health Science. He faces life in prison if convicted on charges of conspiracy to provide material support to al-Qaida, trying to kill Americans and lying to federal investigators.