The FBI suspected within days of the Sept. 11, 2001, terrorist attacks that the American Muslim cleric Anwar al-Awlaki may have purchased tickets for some of the hijackers for air travel in advance of the attacks, according to newly released documents reviewed exclusively by Fox News.

The purpose of these flights remains unclear, but the 9/11 Commission report later noted that the hijackers had used flights in the lead-up to the attacks to test security and surveillance.

The heavily redacted records – obtained by Judicial Watch through a Freedom of information Act request – suggest the FBI held evidence tying the American-born cleric to the hijackers just 16 days after the attack that killed nearly 3,000 Americans.

“We have FBI documents showing that the FBI knew that al-Awlaki had bought three tickets for three of the hijackers to fly into Florida and into Las Vegas, including the lead hijacker, Mohammad Atta,” Tom Fitton, president of Judicial Watch, told Fox News.

He added that the records show the cleric, killed in September 2011 by a U.S. drone strike in Yemen, “was a central focus of the FBI's investigation of 9/11. They show he wasn't cooperative. And they show that he was under surveillance.”

One FBI investigative report known as a 302 summarizes the bureau’s investigation of Al-Awlaki’s Visa transactions. While heavily redacted, the document indicates a credit transaction for “Atta, Mohammed -- American West Airlines, 08/13/2001, Washington, DC to Las Vegas to Miami," the document says.

The mid-August flight, according to the Joint Congressional Inquiry into 9/11, which first investigated the attacks, was one of Atta’s numerous and crucial surveillance flights.

"On August 13, Atta flew a second time across country from Washington to Las Vegas on a Boeing 757 (seated in first class) returning on August 14 to Fort Lauderdale," the 9/11 report reads.

The FBI documents also show a credit card record for a “Suqami, S. ----Southwest Airlines, 07/10/2001, Ft. Lauderdale to Orlando.” Satam al-Suqami was one of the muscle hijackers on American Airlines Flight 11, which slammed into the World Trade Center on Sept. 11.

The third individual, identified in the records is a “W. al-Sheri -- National Airlines, 08/01/2001, San Francisco to Las Vegas to Miami.” This appears to be either Waleed al-Shehri or Wail al-Shehri. The two brothers were also muscle hijackers, according to the 9/11 Commission report.

As part of its ongoing investigation of the cleric, Fox News was first to report in the special “Fox News Reporting - The Secrets of 9/11,” broadcast in September 2011, that the cleric was an overlooked key player in the worst terrorist attack on U.S. soil.

Fox News was also first to report that the cleric was a guest speaker on moderate Islam at a Pentagon executive dining room in February 2002. The newly released documents now suggest the FBI knew five months earlier of al-Awlaki’s probable link to the hijackers.

Fox News was also first to report that al-Awlaki was held at New York City’s JFK airport on Oct. 10, 2002, under a warrant for passport fraud, a felony punishable by 10 years. However, as Fox News was first to document, an FBI agent, Wade Ammerman, from the bureau’s Washington field office ordered the cleric be released from custody, even though there was an active warrant for his arrest.

Fox News’ reporting, which has not been publicly disputed by the bureau, suggests that after the 9/11 attacks the FBI tried to work with al-Awlaki or track him for intelligence purposes. Fitton says the newly released documents raise hard questions for two administrations.

“If he was working for us, to then kill him, that's an extraordinary decision. And we need more information from the administration," Fitton said. "And remember this is not just about the Obama administration. A lot of what we are talking about goes back to the Bush administration. So the Bush administration and the Obama administration need to answer about how Awlaki was handled.”

Fox News asked the FBI for comment on the documents, specifically how the Awlaki lead was pursued in September 2001. Bureau spokeswoman Kathleen Wright responded by saying, “The FBI cautions against drawing conclusions from redacted FOIA documents. The FBI and investigating bodies have not found evidence connecting Anwar al-Awlaki and the attack on Sept. 11, 2001. The document referenced does not link Anwar al-Awlaki with any purchase of airline tickets for the hijackers.”

In response, Judicial Watch said, “the document speaks for itself.” The organization “encouraged the FBI to release the document in its entirety, without redactions, for full transparency.”

Wright said she was not aware of any plans by the FBI to do so at this time.

Click to view the more than 200 pages of documents obtained by Judicial Watch.