More than 10 million people have had power cut to their homes and businesses across Cuba after the country's national electrical grid collapsed for the second time in a week.

Axar.az informs,citing BBC, Cuba's grid operator UNE said it was gradually recovering electricity, prioritising "vital" centres including hospitals and water systems.

The Caribbean country has suffered three major blackouts this month as a US fuel blockade cuts off foreign oil imports, required to keep power stations running.

Cuban Journalist Mag Jorge Castro also wrote on his Facebook several reports have emerged of alarms being activated early this morning in some areas of Havana, along with the presence of black-beret forces preventing residents from staying in building entrances and the sound of helicopters.

He noted that the origin of the situation is unknown, but it cannot be ruled out that military drills are being conducted in response to scenarios such as the recent power system failure.