By Mark Hosenball

WASHINGTON (Reuters) - Prosecutors unsealed an indictment against a son-in-law of Osama bin Laden on Thursday that charged him with conspiracy to kill Americans, after U.S. government sources said he was arrested overseas and brought to New York.

Suleiman Abu Ghaith, a militant who appeared in videos representing al Qaeda after the September 11 attacks in 2001, had initially been picked up in Turkey and was brought to the United States in an operation led by Jordanian authorities and the FBI, the sources said.

The Turkish government deported him to Jordan, the sources said, where local authorities and the FBI took custody of him. He was brought to the United States in the last few days, a law enforcement source said.

U.S. officials including Attorney General Eric Holder announced the indictments on Thursday, saying he would be arraigned on Friday at U.S. District Court in lower Manhattan, only blocks from the site of the World Trade Center, which was destroyed in the September 11 attacks.

Abu Ghaith becomes one of the highest-ranking al Qaeda figures to be brought to the United States for civilian trial. When Holder previously announced plans to try defendants in the September 11 attacks in the same courthouse, he was forced to back down by public opposition, and the trials were moved to the U.S. military base at Guantanamo Bay, Cuba.

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

It also accused him of acting in a conspiracy that "would and did murder United States nationals anywhere in the world," listing actions before and after September 11, 2001.

(Editing by Warren Strobel, Daniel Trotta, Christopher Wilson and Cynthia Osterman)