Maria Ressa

CNN Correspondent

MANILA, Philippines (CNN) -- The FBI was warned six years ago of a terrorist plot to hijack commercial planes and slam them into the Pentagon, the CIA headquarters and other buildings, Philippine investigators told CNN.

Philippine authorities learned of the plot after a small fire in a Manila apartment, which turned out to be the hideout of Ramzi Yousef, who was later convicted for his role in the 1993 bombing of the World Trade Center. Yousef escaped at the time, but agents caught his right-hand man, Abdul Hakim Murad, who told them a chilling tale.

"Murad narrated to us about a plan by the Ramzi cell in the continental U.S. to hijack a commercial plane and ram it into the CIA headquarters in Langley, Virginia, and also the Pentagon," said Rodolfo Mendoza, a Philippine intelligence investigator.

Philippine investigators also found evidence targeting commercial towers in San Francisco, Chicago and New York City.

They said they passed that information on to the FBI in 1995, but it's not clear what was done with it.

One week ago, two hijacked commercial jets slammed into the World Trade Center, collapsing the towers. Another jet hit the Pentagon and a fourth crashed in rural Pennsylvania. Authorities believe that fourth jet may have been headed for the Capitol or the White House. Thousands were killed in the attacks.

On Monday, FBI Director Robert Mueller insisted the agency had "no warning signs" of last week's attacks.

Yousef and Murad both have ties to Osama bin Laden, the man President Bush has labeled the "prime suspect" in Tuesday's attacks.

Authorities also found on a computer in the Manila apartment details of a separate plot to bomb 11 U.S. airliners on overseas flights.

Yousef once listed his occupation as "international terrorist" on an ID card, and he has long been considered a disciple of bin Laden.

Murad was a pilot who admitted he had been trained in Afghanistan as well as the United States. Bin Laden, a Saudi native, lives in Afghanistan.

"(Murad) was principally recruited by Yousef's group and bin Laden's group to undertake a suicide mission," said Avelino Razon, superintendent for the Philippine National Police.

Yousef was eventually caught in Pakistan and brought to New York for trial. He was sentenced to life in prison. Murad is also serving a life sentence.