The European Central Bank has won a legal battle against Bloomberg News to keep some of the ECB’s internal documents secret. The documents could shed light on one of the main causes of the eurozone crisis: How Greece was able to conceal the scale of the debts that it was running up.

Bloomberg went to court to force the publication of certain ECB files. These relate to discussions within the ECB about Greece’s use of derivatives to hide its debt. The ECB successfully argued that publication now would be against the public interest and might aggravate the crisis.

Olivier Hoedeman of Corporate Europe Observatory, which campaigns for greater transparency in European institutions, claims the bank may just be trying to avoid embarrassment:

“The covering up of the real size of Greece’s debt is a very controversial issue and if the documents show that the ECB was aware of what was going on at an early stage that would be a major scandal.”

But the European Court in Luxembourg rejected Bloomberg’s case and ruled that — for  the sake of financial stability — the ECB  should be able to keep its decision making processes secret.