A cross-border power blackout on Monday paralysed the Iberian Peninsula for most of the day, disrupting millions of lives across Spain and Portugal – even interrupting the French electrical system. The sweeping power outage that hit Spain and Portugal this week has raised questions about the electricity grid in a region not normally known for blackouts.

Spain and Portugal experienced a widespread power outage on Monday, leaving millions without electricity in a snap blackout. In Portugal, official sources told domestic media that the outage, which hit around late morning local time,

The hunt has begun for the cause of a massive blackout across Spain, Portugal and parts of France that halted trains, bank machines and traffic lights, in one of Europe's biggest ever power system collapses.