US prosecutors have added two new charges to an indictment against Osama bin Laden's son-in-law, Suleiman Abu Ghaith, who stands accused of conspiring to kill Americans.
A superseding indictment filed with the US District Court in Manhattan on Friday alleges that Abu Ghaith also provided material support and resources to terrorists and conspired to do so.
The indictment details a 2002 speech in which Abu Ghaith, who once served as a spokesman for al-Qaeda, allegedly praised the 9/11 attacks in the United States and warned that more strikes were coming.
"We were also granted victory when the world saw with its very own eyes what the mujahidin did for the sake of God the Almighty in New York and Washington," Abu Ghaith allegedly said.
Kuwaiti-born Abu Ghaith also spoke of planning to target American and Jewish interests "inside and abroad," threatening to launch attacks on the US "at a time, place, and a method of our choosing," according to court documents.
Stanley Cohen, a lawyer for Abu Ghaith, declined to comment on Friday, saying he had yet to review the indictment.
Abu Ghaith previously pleaded not guilty to charges that he conspired to kill Americans in his role as al-Qaeda's spokesman after the 9/11 attacks. Prosecutors allege he issued a call to Muslims, saying "jihad is a duty" and insisting "the storm of airplanes will not stop".
Nearly 3,000 people died on September 11, 2001, when hijacked planes flew into the World Trade Centre and the Pentagon. Another plane crash-landed in a Pennsylvania field.
US forces in Pakistan killed bin Laden, who allegedly masterminded the attacks, in May 2011.
Last month, Abu Ghaith failed in his attempt to suppress statements he had made while being interrogated by FBI agents as he was being flown to the United States to face the original indictment.
His trial is scheduled to begin on February 3, 2014.