Cuba's national electricity system suffered a complete collapse on March 16, state utility Unión Eléctrica announced, plunging the entire island into darkness as the country grapples with an acute fuel shortage.

The utility said "protocols for the restoration of the system are beginning to be implemented" but did not provide a timeline for when power might be restored.

The total grid failure represents the most severe disruption yet to an electricity system that has been buckling under the weight of dwindling petroleum reserves. Blackouts affecting up to 70% of the country during peak hours had already become routine in recent weeks, with residents in several provinces enduring outages of up to 20 hours daily.

Cuba has received no oil shipments in over three months following a de facto US fuel embargo. Venezuela had supplied the bulk of Cuban petroleum for over two decades until the January 3 US operation that resulted in President Nicolás Maduro's capture and severed Caracas's subsidised oil flows to Havana.

President Donald Trump signed an executive order on January 29 declaring Cuba an "unusual and extraordinary threat" to US national security and threatening punitive tariffs against any country supplying oil to the communist-run island. This prompted Mexico, another key oil supplier, to halt deliveries, fearing retaliation from the US.

The island generates roughly 40% of its petroleum from domestic sources but requires imported oil to meet energy demand, with electricity production dependent on ageing Soviet-era oil-fired plants.

On March 15, Trump told reporters aboard Air Force One that Washington could reach an agreement with Cuba imminently. "Cuba also wants to make a deal, and I think we will pretty soon either make a deal or do whatever we have to do," he said.

Cuban President Miguel Díaz-Canel confirmed last week that officials had held talks with US representatives aimed at resolving bilateral differences through dialogue, marking the first public acknowledgement of discussions between the two governments.

The total blackout comes amid mounting social unrest. Over the weekend, protesters in the central city of Morón stormed a provincial Communist Party building, setting it ablaze in anger over soaring food prices and relentless power cuts.