Electricity was back in most of the two countries almost 18 hours after a blackout that shut down much of daily life. The cause of the outage remained unclear.

Electricity had been restored to most of Spain and Portugal early on Tuesday after huge nationwide blackouts, although authorities were still trying to find out what caused the sudden outage.

The cause of the power outage that severely disrupted life in Spain and Portugal on Monday remains a mystery as service was brought back to the Iberian Peninsula.