MADRID/LISBON (Reuters) -A huge power outage brought parts of Spain and Portugal to a standstill on Monday, grounding planes, halting public transport, causing panic buying and leaving the two countries scrambling to restore power to millions of homes and businesses.

A widespread and unexplained power outage knocked out electricity in most of Spain and Portugal on Monday, shutting off traffic lights and causing chaos at airports, train stations and on the roads.

A major power outage in Spain and Portugal has knocked out subway networks, traffic signals and ATMs. Spanish power distributor Red Eléctrica said resto