The EU on Friday formally requested that Meta detail steps it is taking on transparency after the Facebook and Instagram owner scrapped a widely-used tool for tracking disinformation online.
Meta has been criticised on both sides of the Atlantic over the decision to shut down CrowdTangle -- a feature considered vital by researchers tracking viral falsehoods -- in a year of major election contests in the United States and elsewhere.
Unavailable since August 14, CrowdTangle is to be replaced with Meta's Content Library -- a technology researchers say offers nowhere near the same functionality.
The European Commission's request to Meta was sent under the bloc's Digital Services Act, a landmark new law that cracks down on illegal content online.
Brussels launched a formal investigation into Meta's Facebook and Instagram in late April, five weeks before bloc-wide elections in June, over concerns the platforms were failing to counter disinformation.
It raised the alarm in particular at plans to scrap CrowdTangle without an adequate alternative in place.
In its latest request, the commission asked Meta to provide details by September 6 on how it intends to give researchers access to publicly-accessible data on its platforms, and how it plans to update its election monitoring functionalities.
"Specifically, the Commission is requesting information about Meta's Content Library and application programming interface (API), including their eligibility criteria, the application process, and the data that can be accessed and functionalities," said a commission statement.
CrowdTangle has been relied on for years by researchers and journalists seeking to track in real time the spread of conspiracies and hate speech on Meta-owned platforms.
Organisations that debunk misinformation as part of Meta's third-party fact-checking program, including AFP, will have access to the Content Library instead -- but the new tool will not be accessible to for-profit media.
Killing off CrowdTangle is seen as a major blow in a year when dozens of countries are heading to the polls.
In an open letter earlier this year, the global nonprofit Mozilla Foundation warned that decommissioning CrowdTangle would be a "direct threat" to the integrity of elections, urging Meta to retain it at least until January 2025.