Cuba's electricity grid collapsed late on Sunday, the state-owned grid operator said, plunging the island of about 10 million people into darkness as blackouts become more frequent.
The outage follows three nationwide blackouts in July and comes as a U.S.-imposed oil blockade further strains the island's ageing energy infrastructure.
The Union Electrica de Cuba gave no further details of the situation in its posts on X and Facebook.
Pressure on the power system has mounted as Cuba struggles to secure fuel imports.
It lost a key source of fuel after an oil blockade imposed by U.S. President Donald Trump, following Washington's January 3 ouster of Venezuelan President Nicolas Maduro.
Venezuela had long been Cuba's primary oil supplier, with imports from Mexico also halted amid increased U.S. pressure.
The power crisis coincides with a cautious opening of Cuba's tightly controlled energy sector, driven by fuel shortages and severe U.S. sanctions.
Havana recently authorized its first foreign-backed fuel import venture and allowed nearly 200 Cuban businesses to participate in wholesale fuel distribution.
