BERLIN (AP) — Volkswagen board chairman Hans Dieter Poetsch says he doesn't expect an internal investigation into the German automaker's cheating of U.S. diesel emissions standards, which became public in September 2015, to be wrapped up by year's end.

Poetsch, who was quoted in Saturday's edition of the Frankfurter Allegemine Zeitung newspaper, said that law firm Jones Day has made good progress in its investigation, commissioned by Volkswagen, but that it will "probably take longer than the end of 2017."

He says it's clear that "Volkswagen made serious mistakes" and the company's cooperating with authorities with the "highest transparency."

He says the company's also trying to inform the public as much as possible "within the legal boundaries" but that while investigations are ongoing "it would be unacceptably risky for the company to present its own report."