The European Investment Bank's decision to keep secret the entire report on how it was misled into lending €400m to emissions-cheating Volkswagen is "not acceptable", according to Green MEP Heidi Hautala.

The Finnish deputy told EUobserver that she thought the whole report should be made public, but it was "outrageous" that the bank did not grant at least partial access to the document.

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"It is really a shame that our European Investment Bank is behaving in this way," she said.

Last week, the European Investment Bank (EIB) told EUobserver that it would not disclose a report written by anti-fraud office Olaf. The document details how German carmaker Volkswagen was able to acquire a €400m loan while keeping from the EIB that it was producing diesel cars with emissions cheating software.

Volkswagen Group had equipped around 8.5m cars with so-called defeat devices, which led to emissions on the road being much higher than in the required laboratory test.

Citizens of the EU in principle have the right to see EU documents, but sometimes there can be exceptions that allow an EU body to keep papers confidential – for example when releasing them could infringe on somebody's privacy or could harm relations with a third country.

However, there is also the possibility to redact documents and then grant partial access.

MEP Hautala is very sensitive to the possibility of partial access, because she fought for it in court two decades ago.

Hautala was among the first Finnish MEPs after that country's accession in 1995, and in 1996 she asked for documents to be released related to arms exports. The request was repeatedly refused by the Council of the EU – where national governments meet.

She went to the Court of Justice and finally won in 2001.

"The legal principle of partial access was established," she said in a phone interview.

Olivier Hoedeman, researcher and campaigner at the Corporate Europe Observatory, agreed with her.

"The EIB's decision to refuse disclosure of the documents is clearly at odds with the transparency rules of the Lisbon Treaty," he told this website in an email, referring to the treaty that has been the legal basis of the EU since 2007.

"EU institutions are obliged to work as openly as possible, especially towards citizens. And there is a clear public interest in EU citizens being fully informed about the scandalous EIB loan to Volkswagen," said Hoedeman.

"To heed the Lisbon Treaty's transparency obligations, the EIB should at the very least have allowed partial access to the documents," he added.

A second campaign group, Bankwatch, expressed similar concerns.

"This is very disappointing that despite the multi-billion euro public support that VW received in the recent years from the EIB, the company remains under the protective umbrella of the EU's institutions," said campaigner Anna Roggenbuck, who follows the EIB's activities.

She criticised the reasons the EIB gave for not publishing the document, which included that "internal discussions and consultations" about the bank should do in response to the Olaf report were still "ongoing".

"Disclosure [of the report] would therefore seriously undermine any final outcome on the bank's consideration of this file," wrote the bank's secretary general, Marjut Santoni.

Roggenbruck dismissed that argument.

"The EU's bank hides behind its sluggish internal investigation to not explain how it was possible the company was getting public money for the environmental improvements whereas it deceived its consumers and threaten the right to clean air for millions EU's citizens," she said.

MEPs also want to see Olaf report

The bank's refusal to publish the report was also a rejection of the European Parliament, which said in a resolution in February that the document should be made available. The demand to have the report published was introduced through an amendment by Hautala.

Last month, the parliament's budgetary control committee held a meeting with EIB representatives – behind closed doors – to discuss the report.

It will be up to the committee's coordinators for the political groups now to decide how to proceed, for example by asking to read the document in a secure reading room. The coordinators will meet this Wednesday (25 April).