Cuba has suffered a massive power outage affecting Havana and the country’s provinces that has left millions in the dark.

Pockets of Cuba's capital Havana saw the lights flicker back on though vast areas of the city and country continued without electricity on Sunday morning, after a nationwide grid collapse that knocked out power to 10 million people.

Cuba reconnected its national electrical grid and restored power to the majority of the capital Havana by late on Sunday, energy officials said, nearly two days after an island-wide outage knocked out power to 10 million people.

Millions of people in Cuba are without power after a failure of the nation’s electric grid left the island in the dark

Cuba remains largely without power a day after the country's grid collapsed, raising fresh questions about the island's generating system; officials gave no timeline for restoring service.

The collapse follows nationwide blackouts last year that plunged Cuba's frail power-generating system into disarray.