Explosives used in Dortmund attack may have come from German military - newspaper

Football Soccer - Borussia Dortmund v AS Monaco - UEFA Champions League Quarter Final First Leg - Signal Iduna Park, Dortmund, Germany - 11/4/17 The Borussia Dortmund team bus is seen after an explosion near their hotel before the game Reuters / Kai Pfaffenbach Livepic

BERLIN (Reuters) - The explosives used in the attack on the bus of soccer team Borussia Dortmund may have come from supplies belonging to the German armed forces, a newspaper cited a source involved in the investigation as saying on Saturday.

It is still unclear who carried out Tuesday's attack. German prosecutors have doubts about the authenticity of letters that suggested Islamist militants were behind it and Bild newspaper cited an investigator as saying right-wing extremists were probably responsible.