FRANKFURT, Sept. 5 — German authorities said Wednesday that they had stopped a major terrorist attack against American and German targets in this country, arresting three Islamic militants and seizing a large amount of potentially explosive chemicals and military-grade detonators.
Those arrested — two German citizens who had converted to Islam and a Turkish resident of Germany — were in the advanced stages of plotting bomb attacks that could have been deadlier than those that killed dozens in London and Madrid, the police and security officials said. At least five lesser figures are still being pursued, they said.
“They were planning massive attacks,” the German federal prosecutor, Monika Harms, said at a news conference, outlining an intensive six-month investigation. She said the suspects had amassed hydrogen peroxide, the main chemical in the explosives used in the London suicide bombings of July 2005.
For months, Germany has been warning of a likely terrorist attack, and the government has been contemplating tightening surveillance and enforcement tactics that are now looser than elsewhere in Europe, in part because of Germany’s troubled 20th-century history.