"There is a lack of transparency and it is possible to hide money in Germany, so it's not surprising we see these scandals. Even when there have been efforts at the E.U. level to introduce transparency, Germany has come out as an opponent," Ryding said.
Germany objected to the development of a centralized data bank of owners as part of an EU anti-money laundering directive proposed at the end of 2014, and opposed public access to the information, the report explains. That directive was later approved, but only members of the public who can prove a legitimate interest in the company's dealings can have access to the central register.
Ryding said the most important action German and Luxembourg could take would be to follow through on their promises.
"Not one single government says they want to help people to hide money. They always say we want to change the system, but they're saying one thing and doing something else," she said.
The spokesperson for Germany's finance ministry was not immediately available to comment when contacted by CNBC.