NEW YORK - Al Qaida spokesman Suleiman Abu Ghaith, a son-in-law of Osama bin Laden, on Friday pleaded not guilty of conspiracy to kill U.S. nationals in a New York federal court.

Suleiman Abu Ghaith, who is married to one of Bin Laden's daughters, made his first appearance on Friday at the federal courthouse in Lower Manhattan, just blocks away from the site of the World Trade Center, where two of the airplanes hijacked by terrorists some 12 years ago struck down the famed Twin Towers, killing tens of thousands of innocent people. He entered the not- guilty plea through a lawyer to one count of conspiracy to kill Americans.

"Among other things, Ghaith urged others to swear allegiance to bin Laden, spoke on behalf of and in support of Al Qaida's mission, and warned that attacks similar to those of September 11, 2001 would continue," according to the indictment.

It accused him of involving in a plot that "would and did murder United States nationals anywhere in the world."

Local media quoted Republican Representative Peter King, former chairman of the House Homeland Security Committee, as saying that Ghaith was captured within last week in Jordan, which was considered as a "very significant victory" in the effort against Al Qaida.

"No amount of distance or time will weaken our resolve to bring America's enemies to justice," said Attorney General Eric Holder.

According to the U.S. Attorney for the Southern District of New York Preet Bharara, it has been 13 years since Ghaith allegedly worked alongside Osama bin Laden in his campaign and 13 years since he allegedly took to the public airwaves, exhorting others to embrace Al Qaida's cause.

Bail was not requested, and the prosecutors said they expected the trial to last three weeks, although no starting date has been announced.