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

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.

A residential building crumbled on Saturday night in the Centro Habana district of the Cuban capital, as the city was engulfed in darkness due to a