Cuba said it had reconnected its electrical grid and was gradually restoring power after a partial collapse on Wednesday left the capital Havana and much of western Cuba in the dark — the latest incident in an energy crisis that has left millions suffering from prolonged blackouts for months.

Top energy officials said a main transmission line connecting Havana with the country's largest power plant in Matanzas failed at about 5 a.m. ET but that workers had restored power to about 40 per cent of the capital city by midday.

At least four western provinces, from Pinar del Rio to Mayabeque, lost power early on Wednesday, officials said, though all had been reconnected to the grid within hours of the outage.

A police officer directs traffic in Havana during Wednesday's outage. (Ramon Espin

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