Portugal's energy minister says a report by the Spanish government into the mass power outage that hit the neighboring southern European countries in April lacks clarity, and that it is waiting for an independent report by the European Union's Agency for the Cooperation of Energy Regulators to establish the real cause of the incident.

The World Economic Forum has said the sudden outage on April 28 left tens of millions of people in both countries without power, and caused huge disruption to transport, banking, and communication networks, with hospitals forced to resort to using back-up generators.

"The blackout made it clear there is a need for greater modernization, digitalization of the grids, applying data science, storing data, in order to understand what is happening in a more complex system and reacting to it," said Minister for Environment and Energy Maria da Graca Carvalho. "It requires investment and we have been asking the European Commission to guide Europe in this investment and also help co-finance it, because it is also a security issue."

The Spanish government report suggests that national grid operator Redeia had miscalculated the correct mix of energy in the system, but it also says some thermal power plants using nuclear, coal, and gas were at fault for failing to keep voltage levels up.

Spain's Minister for Ecological Transition Sara Aagesen, who has responsibility for energy policy, said a number of small grid failures, mainly in the south of the country, had caused a chain reaction, which then also impacted Portugal.

According to the Euronews website, in just five seconds, around 60 percent of Spain's electricity supply was lost, before being restored in the early hours of the following day.

Any suggestion that a cyberattack had been the reason was categorically rejected, as were suggestions that Spain's renewable energy output was a contributory factor.

Spain is one of the leading lights in Europe's transition to renewables and is in the process of phasing out its nuclear plants. In 2024, the nation generated almost 57 percent of its electricity from renewable sources.

The European Commission estimates that, in order to achieve its clean-energy transition goals, the 27 EU member states must invest 584 billion euros ($684 billion) by 2030 on enlarging and updating electricity grids. A public consultation on the issue is ongoing and should be completed by the end of this year.

Alberto Nunez Feijoo, the leader of Spain's main right-wing opposition People's Party, said that Prime Minister Pedro Sanchez was "so intent on being the greenest in the world that you have led Spaniards into the dark".

julian@mail.chinadailyuk.com