A police spokesperson said the men were suspected of planning 'massive bomb attacks' on US installations on German soil.
The men, two Germans and a man with both Turkish and German citizenship, are also accused of belonging to a domestic cell of the Islamic Jihad militant group.
Police say the men had obtained enough materials to make a bomb with an explosive power equal to 550kg of TNT and said that an attack appeared imminent.
The three were arrested yesterday at a house they had rented in the Sauerland region of North Rhine-Westphalia in western Germany.
Between February and August 2007, they had acquired 12 vats and a hydrogen peroxide solution used in bomb-making.
Germany, which has forces stationed in Afghanistan, has been on high alert for attacks for some time. The country has feared a re-emergence of Islamist groups since 2001, when the northern city of Hamburg was used as a base for planning the 11 September attacks.
The arrests came one day after Danish police took eight people into custody during raids in Copenhagen.
