The Commission said its "reply letter confirms the willingness of the Commission to keep the dialogue with Slovenia on this matter open in the spirit of sincere cooperation, as with all member states".

Janša has said he inquired in the letter whether there was any chance that the Commission withdraw the lawsuit.

According to Delo's online portal, the Commission head replied that she appreciated the prime minister's willingness to reach an agreement on the matter, and that relevant Commission services were ready to cooperate with the Slovenian authorities on the case in the search of a better insight into the possibilities to solve the problem in line with what Slovenia is proposing.

Von der Leyen reportedly called for direct communication, and noted that the Commission expected full respect of the independence of Slovenian central bank Banka Slovenije and its governor.

Janša is scheduled to meet von der Leyen in Brussels on Thursday, so the issue is expected to come up at the meeting.

The case dates back to 2016, when Slovenian police seized some European Central Bank (ECB) documents when seizing the Banka Slovenije governor's laptop in a house search at Slovenia's central bank carried out as part of an investigation into alleged wrongdoing in the 2013 bank bailout in Slovenia.

The ECB and the Commission maintain that the seized documents fall under the principle of immunity of EU or ECB documents and could not be used in the investigation.

Slovenia meanwhile disagrees, insisting that the concept of privileges and immunities is defined much more narrowly in international law than it is interpreted by the Commission.

But in June, ten days before the first oral hearing at the European Court of Justice (ECJ), news broke that Janša had written to van der Leyen to see under which conditions the Commission would be willing to withdraw the lawsuit.

Slovenia's agent Katja Rejec Longar labelled the June hearing "very positive" for the country. Asked whether a settlement would be possible, she said the Commission always had the option of admitting a mistake and withdrawing the suit.

But a settlement is not possible in the sense that Slovenia says it seized the EU's archives, because Slovenian courts have ruled that the seized documents are not the EU's archives, and these rulings are binding on Slovenian institutions, she explained.

ECJ Advocate General Juliane Kokott said she would present her opinion on the matter, which is not binding on the court, on 3 September.

The court does not want to specify when the ruling could be delivered. However, since similar cases last year ended about 19 months after the suit was filed, the ruling is expected towards the end of the year.

The Commission can withdraw the suit at any stage of the process until the ruling is delivered.

The case is considered a precedence because immunity of EU archives has rarely been discussed in courts, thus the ruling in this case would be important for all EU members to see how the court defined its use.