Cuba’s communist government is facing its toughest challenge since the 1991 collapse of the Soviet Union as days of nationwide power failures cripple an island already suffering from severe shortages of food, fuel and medicine.

The national grid has collapsed four times in the past four days, leaving most of the country, including the capital Havana, without power. Residents were reduced to carrying buckets of water from cisterns or wells to their houses and queueing longer than usual for bread and other basic necessities.

Small anti-government protests broke out over the weekend around the island, and President Miguel Díaz-Canel appeared on state television wearing military fatigues on Sunday night to warn Cubans not to take part in “vandalism”.