"The commission is hereby taking legal steps to ensure the development of renewable energy across the EU and to reduce greenhouse gas emissions, energy dependency and high prices," it said in a press release.

The renewable energy directive, adopted in 2018, provides the legal framework for developing renewable energy in electricity, heating and cooling, and transport this decade. Member states were required to transpose the directive by June 30, 2021.

Croatia, Hungary, and Portugal are the only three member states who have failed to notify any correlation table or explanatory document specifying where they have transposed each provision of the directive, the commission added.