The blaze in an apartment block mostly inhabited by people of Turkish descent prompted speculation in the Turkish media that it was a racially motivated attack.
But local chief prosecutor Lothar Liebig, who had received a police report, said the flames had broken out from a smouldering fire in the cellar. Police declined to speculate on the source of the fire.
Arson was extremely unlikely not least as the fire occurred during carnival celebrations when about 60 people were present.
"Any perpertrator who got into the house would have run a high risk of being discovered," said Liebig, adding there was no indication of an attack.
He said investigators found no evidence of a fire accelerant, and ruled out an electrical fault because there was no wiring in the area where the fire broke out.
Five children and a pregnant woman were among the dead and pictures of a baby who was thrown to safety out of an upstairs window made newspapers around the globe.
Turkish experts joined German police in their investigations and Prime Minister Tayyip Erdogan visted the site after Turkish newspapers reported that a family who lost members in the blaze had been threatened by neo-Nazis.
Germany is home to at least 2.5 million people of Turkish descent.
Last Mod: 04 Mart 2008, 17:44