Electricity outages have paralyzed an already-crippled economy, leading to shortages of everything from cash to running water.

Cuba's efforts to restore power to the island were derailed for a third time late on Saturday, Cuban authorities said shortly before midnight, leaving millions in the dark and raising fresh questions over the viability of the government's bid to reestablish electrical service.

Cuba's power-grid operator said it had restored electricity to parts of the capital Havana on Monday following a fourth major grid failure in 48 hours, while Tropical Storm Oscar lashed the island's eastern end.