An Islamic extremist couple allegedly planned a terror attack in southern Germany, local media reported.
Explosives and weapons were found in the home of the couple near the town of Oberursel, north-west of Frankfurt, reports Die Welt.
The newspaper identified the pair by their first names Halil and Senay D, and alleged that Halil had links to Islamist circles in Frankfurt and to terror group al-Qaeda.
Police placed them under surveillance after they used false names to buy significant quantities of chemicals that can be used to made explosives, reports the newspaper.
After searching their home, police found a pipe bomb, bomb detonation tools, explosives, an assault rifle and ammunition.
When Halil was spotted surveying an area where popular bicycle race is due to pass tomorrow (1 May) police arrested the couple.
Police confirmed the arrest and said that more properties were being searched in connection with the case.
Germany's BfV intelligence agency estimates that 450 German citizens have travelled to Syria to join extremist Sunni organisation Islamic State.
In Braunschweig, northern Germany, a parade was called off at the last minute after a "specific threat of an Islamist attack" was detected by security services.