Havana, Cuba - Cuba struggled to restore power Monday after another nationwide blackout amid the Trump administration's devastating fuel embargo.

In pitch-black Old Havana, residents stood on balconies and hung out of windows thumping kitchenware and clapping in an hour-long protest at a power cut that began on Sunday.

The island is struggling to keep the lights in large part due to a biting US energy blockade.

Most Cubans now have power only for a few hours a day at best, making normal life nearly impossible.

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And countrywide grid collapses are becoming more common.

With each outage, water supplies trickle away, and ceiling fans slow to a halt.

Carlos Duenas, a 62-year-old mechanic, said he felt worn out by the "unsustainable" situation.

"No one says when the situation might improve. In the meantime, we just have to endure," he said. "Not everyone has the money to buy (solar) panels."

As the lights suddenly turned off across Havana late Sunday, residents sitting outside to get some respite from the summer heat audibly groaned.

By midday Monday, about 50% of Havana had electricity restored, as well as seven provinces in central and western Cuba.

The state electricity firm said efforts to restore power had been hampered by bad weather.

"We continue to work intensively to remedy the situation and reset the system as quickly as possible," the utility, UNE, said.

The fuel shortages are causing a huge strain for Cuban society – with no obvious end in sight.

"Since Friday I've only had an hour and a half of electricity. There's no water, there's nothing. What we Cubans are living through is not a life," Mayra Rodriguez, a 43-year-old accountant, told AFP.

She sleeps on her apartment balcony with her two small children to cope with the summer heat.

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Many of Cuba's electricity production facilities run off fuel oil, diesel or natural gas, which are no longer regularly arriving in Cuban ports.

Washington has warned countries they will face sanctions if they deliver oil to Cuba – a threat Havana's longtime allies have not been willing to openly test.

The administration of President Donald Trump has authorized the arrival of only one Russian tanker carrying 100,000 tons of crude, which came in March. Those reserves have since been exhausted.

In addition to enacting an oil blockade, the Trump administration has ramped up sanctions against Cuban state-owned businesses, prompting many foreign companies to suspend operations in the country.

The US has also indicted former President Raul Castro, brother of revolutionary leader Fidel Castro, over the downing of two civilian planes three decades ago.

Talks between Havana and Washington appear to have amounted to little, while Cuba has enacted a series of market reforms to give the economy a boost.