A failure of the interconnection between the grids of Spain and France caused the massive power outage that hit most of the Iberian Peninsula on Monday, La Vanguardia newspaper reported, quoting Spanish grid operator REE's system operations chief Eduardo Prieto.

Millions of people in Spain, Portugal and parts of southern France lost power on Monday following a "severe disruption" in the European electrical system, the Spanish prime minister said. The cause of the disruption is still unknown,

Spain, Portugal and parts of France were plunged into chaos after power outages grounded flights, stopped trains and left whole cities without electricity or phone signal.