Miguel Afonso Caetano"A fire in the south-west of France, on the Alaric mountain, which damaged a high-voltage power line between Perpignan and eastern Narbonne, has also been identified as a possible cause, Portugal's national electric company REN said.
Reports on a rare atmospheric phenomenon which have also been circulating have been denied by REN to private channel SIC.
Meanwhile, the Spanish National Intelligence Centre has not ruled out the possibility of a cyberattack, while the Portuguese government has also suggested the same.
However, "no evidence has yet been identified that points to a cyberattack" to justify the blackout, Portugal's National Cybersecurity Centre (CNCS) said in a statement on Monday.
"Such a widespread grid failure is extremely unusual and could be caused by a number of things: there could be a physical fault in the grid which brings down power, a coordinated cyber attack could be behind it, or a dramatic imbalance between demand and supply has tipped the grid system over the edge," Taco Engelaar, managing director at energy infrastructure experts Neara told Euronews."
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