Millions of people were left without power in Cuba on Wednesday - the latest in a string of blackouts to hit the island as it struggles with fuel shortages worsened by pressure from the US.

Two-thirds of the island was plunged into darkness following what officials described as an "unexpected" shutdown at one of the country's main power plants.

Cuba's national electricity company, UNE, said the blackout affected a vast area stretching from the central province of Camaguey to Pinar del Rio in the west, and including the capital, Havana.

Cuba has been hit by a wave of power cuts in recent years, with chronic fuel shortages exacerbated by a US blockade on oil from key ally Venezuela since January.

The communist nation is also suffering from a shortage of aviation fuel, leading several airlines to suspend services there and limiting international tourism. Air France became the latest carrier to do so on Wednesday.

The cause of Wednesday's outage was sparked by a breakdown at the Antonio Guiteras thermometric plant, about 100km (62 miles) east of Havana, authorities said.

The national electricity company said efforts were under way to restore services.

The blackout is the second outage to affect Cuba's western region in the past three months.

Creaking infrastructure has been compounded by fuel shortages, resulting in a crisis that has disrupted public transport and rubbish collection.

Cuba, which relies heavily on imported fuel to generate electricity, has partly survived crippling Western sanctions due to the help of its allies in the region, including the left-wing Venezuelan government.

Venezuela was believed to have sent around 35,000 barrels of oil a day to Cuba - providing about half the island's oil needs - before the former's President Nicolas Maduro was captured by US forces in early January.

Since then, the US has seized a number of shipments of oil bound for Cuba.

Power cuts lasting up to 18 hours a day have affected hospital emergency wards, dialysis patients and pumping stations.

The US and Cuba have had a strained relationship since the communist Fidel Castro overthrew a US-backed government in 1959. US economic and trade embargoes on Cuba have been in place since 1960.

US President Donald Trump has made no secret of his desire for a change of leadership in Cuba, threatening tariffs on goods imported into the US from any country that provides oil to the Caribbean nation.

Air France said it was halting services to Havana from the end of March until mid-June, citing fuel shortages.