The FBI believes it found weapons belonging to a terror suspect who trained at the same Atlanta flight school as two of the Sept. 11 hijackers and who was recently detained but has since been released, FOX News has learned.

Zayead Christopher Hajaig (search), a Nigerian-born Briton, was arrested in London on April 8, shortly after the FBI's Joint Terrorism Task Force issued a worldwide alert for him. Sources at the bureau told FOX News that Hajaig was questioned and released; authorities believe he is still in Britain.

FBI sources told FOX News that a person linked to Hajaig contacted the FBI's Atlanta bureau and turned over a number of weapons said to have been owned by the suspect.

The tipster also told authorities that two other weapons were dumped into the Chattahoochee River (search) at Hajaig's behest. One of the weapons described was recovered in a search of the river by the Cobb County dive team on Tuesday.

It was unknown if the weapons had been used in any crimes or were intended for use in a future plot.

An FBI spokesman would not comment on Hajaig's whereabouts or why he was released by British authorities. An investigation by the bureau and Immigration and Customs Enforcement was ongoing, a press release said.

Hajaig, 35, had aroused suspicions of flight instructors at Gwinnett County Airport, where lead Sept. 11, 2001, hijacker Mohamed Atta (search) and fellow hijacker Marwan al-Shehhi had trained. Hajaig was living in the United States illegally but was still able to obtain a pilot's license from the Federal Aviation Administration in April 2002, authorities said.

Hajaig apparently pushed to have his pilot rating upgraded despite being underqualified. The Joint Terrorism Task Force warning said he became "aggressive and attempted to have the flight school accelerate his training."

Hajaig was placed on a no-fly list, and was described by an FBI spokesman as a "person of interest" in terror investigations.