The FBI had a mole inside al Qaeda who met with Osama bin Laden eight years prior to 9/11 and knew he planned to finance terror attacks, but the bureau declined to tell Congressional investigators or the 9/11 Commission about the mole, sources involved in the case told NBC News.

The mole, NBC News has learned exclusively, was a Los Angeles-based “driver and confidante” of the “Blind Sheikh,” Omar Abdel-Rahman, now in prison for his role in planning the original 1993 terror attack on New York’s World Trade Center. Information from the mole helped stop a bin Laden-backed plot against a Masonic Lodge in L.A. in the mid-‘90s, according to courtroom testimony by Ed Curran, who was the assistant special agent in charge of the FBI’s L.A. office at the time.

"It was the only source I know in the bureau where we had a source right in al Qaeda, directly involved," Curran told the court, according to excerpts of testimony published by the Washington Times. He also testified that the informant was “tight, close” with al Qaeda leadership.

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Curran said the agent handling the source got the source to go overseas and meet with bin Laden, and that bin Laden told the source he had “picked out” a Masonic Lodge in L.A. for an “explosion.”

Sources told NBC News that the informant also revealed Osama bin Laden provided financial support for terror operations. The mole told the FBI that the Blind Sheikh said, “If you need any money, you go to Osama directly and tell him I sent you.”

The existence of the mole was first disclosed during Curran’s 2010 testimony in support of a lawsuit filed against the FBI by Bassem Youssef, an agent assigned to the terrorism squad in L.A. who had developed and run the mole. Youssef, the highest-ranked Arabic speaker in the bureau, accused the FBI of discriminating against him and passing him over for promotion to supervisor despite his skills. The Washington Times, the first media outlet to report on Curran’s revelation about the mole, noted in its report that Curran was testifying before a virtually empty courtroom.

The testimony by FBI agents in the suit was at times embarrassing -- with senior FBI officials admitting they did not know a Shiite from a Sunni, and insisting that Arabic language skills were not crucial.

Former Rep. Lee Hamilton, the Indiana Democrat who co-chaired the 9/11 Commission, told the Washington Times he didn’t believe the FBI had ever mentioned the existence of the al Qaeda source during the Commission’s investigation of the 2001 terror attacks on the World Trade Center and the Pentagon.

In a statement, FBI Assistant Director Michael Kortan said the bureau had made "all relevant information available to the 9/11 Commission and the joint intelligence community inquiry. Throughout both of these reviews, the FBI shared pertinent documents and knowledgeable personnel in order to present all known information to commission and inquiry personnel."

The Egyptian-born Youssef filed suit against the FBI in 2003, alleging that the Bureau retaliated against him after he lodged complaints against the counterterrorism unit. In 2008, he told Congress that the FBI was unable to protect the U.S. against a major attack from Middle Eastern terrorists. He also criticized the agency for a shortage of Arabic speakers, and said it relied on translation services.

Youssef remains with the agency and is still pursuing his discrimination claim.