BERLIN (AP) — German automaker Volkswagen says a study into its role during Brazil's 1964-1985 military dictatorship has concluded that some site security officials in Brazil cooperated with the regime but there was no clear evidence the collaboration was "institutionalized."

Volkswagen has faced accusations it collaborated with the military government and drew up blacklists on employees. The company last year commissioned Christopher Kopper, a history professor at Germany's Bielefeld University, to examine its role.

The company said Thursday that Kopper had concluded "there was cooperation between individuals of site security at Volkswagen do Brasil and the former military regime. But there is also no clear evidence found that the cooperation was institutionalized by the company."

Kopper's report said he found no clear evidence of "material assistance" for operating a military torture center.