Venezuela's socialist government is blaming a nationwide blackout on an "electromagnetic attack" against the nation's hydroelectric system.

Communications Minister Jorge Rodriguez read a statement broadcast on social media Monday in which he said authorities were working to restore service as quickly as possible. He appealed for calm and said contingency plans had been activated so that medical facilities would not be affected. He said security forces were also being deployed to guarantee peoples' safety.

Authorities attributed an almost week-long outage across Venezuela in March to a U.S.-sponsored electromagnetic attack on the Guri dam, source of around 80% of the nation's power. But government opponents laid bare years of underinvestment in the nation's grid by corrupt officials who mismanaged an oil bonanza in the nation sitting atop the world's largest crude reserves.