German Defense Minister Franz Josef Jung made the announcement on state television but offered few details, Deutsche Welle reported.

"There was an imminent security threat," he said, suggesting the attacks on the airport and the military base at Ramstein in southwestern Germany were scheduled to coincide with the anniversary of the Sept. 11, 2001, attacks on the United States.

Two of the men arrested in the raid Tuesday night in a village north of Frankfurt were German nationals who had converted to Islam while the third was Pakistani, and all the men were in their 20s, the report said.

Federal Prosecutor Monika Harms said the amount of hydrogen peroxide and other chemicals seized would have had the explosive power of 1,200 pounds of dynamite, the report said.

Jorg Ziercke, head of Germany's Federal Criminal Police Office, told reporters more than 300 police officers had spent six months monitoring the men.