The EU's internal watchdog has criticised as "problematic" the European Commission's defence over its refusal to release text messages between President Ursula von der Leyen and the CEO of Pfizer.
The EU Ombudsman had called on the bloc's executive to share the controversial exchanges about the EU's purchase of vaccine contracts.
The text exchange was reported by a New York Times reporter in April 2021.
The Commission, however, said in a response released on Wednesday that "the search undertaken by the president’s cabinet for relevant text messages corresponding to the request for access to documents has not yielded any results."
"Due to their short-lived and ephemeral nature, text and instant messages, in general, do not contain important information relating to policies, activities and decisions of the commission, nor are they in the possession of the institution," Commission Vice-President Věra Jourova wrote in the response.
She added that the Commission would "reach out to all the other institutions of the Union and propose that they draw up together guidance for their staff on the use of modern communication tools such as text and instance messages."
More than half of the 4.2 billion COVID-19 vaccines reserved by the EU were supplied by the American-German company Pfizer/BioNTech.
But NGOs and MEPs have expressed concern that key aspects of the contracts with the laboratories have remained confidential.
Following a request by the New York Times, the Commission had released three documents, but not text messages between von der Leyen and Pfizer boss Albert Bourla.
EU ombudsman Emily O'Reilly called the Commission's response on Wednesday "problematic" but said that a full analysis would be published in a couple of weeks.
In January, she had asked the EU Commission to carry out "a more thorough search" for the text messages.
She criticised the fact that "no attempt had been made" to do so, saying that such a "way of acting did not meet the expectations of transparency" on public access to EU documents.
"In the context of the Ombudsman’s inquiry, it emerged that the Commission does not consider that text messages generally fall under its internal criteria for document recording, due to the short-lived nature of their content," the statement read.
"The Ombudsman considers that this constituted maladministration."