Power began returning to households in Spain and neighbouring Portugal, hours after cities across the Iberian Peninsula were plunged into darkness in one of Europe's most severe blackouts.Investigators are still looking into the cause of the blackout which remains 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.

A widespread power outage hit Spain and Portugal, affecting millions of people who live across Europe's Iberian Peninsula.