MADRID (Reuters) -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 complete restoration of electricity in Spain and Portugal might take between six to ten hours following a widespread blackout that left millions

Electricity has been restored to almost 90 percent of mainland Spain after a massive blackout in the Iberian Peninsula on Monday. According to the national electricity grid operator Red Electrica de Espana (REE),