Power cuts have impacted as many as 50 million people across Spain and Portugal - causing huge disruption to public transport, airports and vital telecommunications networks

A sudden, widespread blackout plunged most of Spain and Portugal into darkness, disrupting everyday life and causing chaos across the region. After hours of uncertainty, power is gradually returning, but questions about the cause remain unanswered.

Several airports, including Madrid airport, which is Spain's busiest, had no electricity, El Mundo reported. Major cities including Barcelona, Seville and Valencia were without power. Parts of France were also affected by power loss.