Robert Hutchings, chairman of the National Intelligence Council which reports to the CIA director, did not give details of the plots but provided the most recent public outline from an intelligence official of the al-Qaida threat.
Hutchings said the outlawed outfit planned to fly hijacked planes into targets as they did during the September 11 attacks.
"Soft targets, including the US stock market, banks, major companies, and tall buildings are a primary focus of active al-Qaida planning," he said.
Addressing the International Security Management Association in Arizona, Hutchings said nuclear power plants, water treatment facilities and other public utilities were high on al-Qaida's target list.
"My biggest worry, however, is how far al-Qaida might have progressed in being able to deploy a chemical, nuclear or biological weapon against the United States or its allies," he said.
Hutchings said though much has been done to thwart terror-attacks, dangers still lurked.
"Although we have disrupted several airline plots, we have not eliminated the threat to airplanes," he said. "There are still al-Qaida operatives who we believe have been deployed to hijack planes and fly them into key targets."|