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

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

This image made available by Al-Jazeera shows Sulaiman Abu Ghaith, Osama bin Laden's son-in-law and spokesman. Abu Ghaith has been captured by the United States, officials said on Thursday. [Al-Jazeera via Associated Press]

The sources said the Turkish government deported him to Jordan, 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.

US officials, including Attorney General Eric Holder, announced the indictment on Thursday, saying he would be arraigned on Friday at US District Court in New York City's lower Manhattan, only blocks from the site of the World Trade Center, which was destroyed in the Sept 11 attacks.

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

New York police are less concerned that Abu Ghaith's case will present a security problem than they were about the trials of Khalid Sheikh Mohammed and four others charged with plotting the attacks, a law enforcement source said.

"It's not the same. It doesn't rise to that level," said the source, who is familiar with the department's views and spoke on condition of anonymity.

The indictment accused Abu Ghaith of acting in a conspiracy that "would and did murder US nationals anywhere in the world," listing actions before and after Sept 11, 2001.

"Among other things, Abu 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 Sept 11, 2001, would continue," the indictment said.

Initial public confirmation of Abu Ghaith's capture came from US Representative Peter King, a senior Republican member of the House of Representatives' Intelligence Committee and former chairman of the House Committee on Homeland Security.

"I commend our CIA and FBI, our allies in Jordan, and President (Barack) Obama for their capture of al-Qaida spokesman Sulaiman Abu Ghaith. I trust he received a vigorous interrogation, and will face swift and certain justice," King said in a statement.

US sources indicated that while a CIA role in the capture of Abu Ghaith could not be ruled out, the FBI took the lead role in the operation under the auspices of an interagency body known as the High-value Detainee Interrogation Group.