What we know about the cause of Spain's nationwide blackout

Millions of people across Spain, including in Barcelona, Madrid, Bilbao, Valencia and Málaga were left without power for several hours from 12:30pm on Monday, causing metro systems to grind to a halt, train stations to close, businesses to shut up shop and chaos on the roads.

The only places that were working as normal were hospitals which had backup generators and some big supermarket chains, which had the same solution.

The blackout also caused problems in neighbouring Portugal and in some areas of France.

Some cities, such as Barcelona had their power back up and running just after 3pm, but other places were still left without it.

National grid operators Red Eléctrica warned it could take between six and ten hours to restore power to the whole country.

Do we know what caused the blackout?

At the time of publication the exact cause of the mass power cut was still unknown, or at least hadn't been made public.

The government said it was urgently investigating the cause.

"The government is working to identify the origin of this incident and dedicating all possible resources to resolve it as quickly as possible," Prime Minister Pedro Sánchez's office said.

Sanchez visited the headquarters of the state electricity network operator to be briefed and the announced the government would hold an emergency meeting at its headquarters in Moncloa in Madrid.

Spain’s national security council also convened as the crisis unfolded.

The Portuguese electricity grid operator is saying it could have been caused by a rare atmospheric phenomenon in Spain, caused by extreme temperature fluctuations in the interior of the country.

There were also reports from Spanish news outlets, however, saying that Spanish government and the European Union were investigating the power cut as a possible cyberattack.

Reports from neighbouring Portugal also suggested a cyber attack was to blame.

The European Commission was in contact with Spain and Portugal "to understand the underlying cause" of the outage, a spokesperson said.

Brussels has indicted that there has been an "unprecedented wave of cyberattacks" across Europe recently that has affected some type of operations in at least 15 different countries.

EU security agencies have pointed the finger at Russian state-backed groups as suspects, although the Kremlin has officially denied involvement in the Spanish blackout and dismissed the accusations as "baseless and provocative".

The head of operations for Spain's grid operator Red Electrica , Eduardo Prieto, added that everything was being done "to shed light" on the origin of the power cut.

The operator suggested it may have been due to a strong oscillation of power flow, but that the origin is unknown.

Massive blackouts have affected other countries around the world in recent years.

Huge outages struck Tunisia in September 2023, Sri Lanka in August 2020, and Argentina and Uruguay in June 2019. In July 2012, India experience a vast blackout.

In Europe, in November 2006, 10 million people were left without power for an hour in France, Germany, Belgium, the Netherlands, Italy and Spain. That was caused by a failure in Germany's grid.