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.

Cuba's energy ministry said in a social media statement that "a total disconnection of the National Electrical System has occurred".

Cuba's grid operator, UNE, said it was gradually restoring electricity, prioritising "vital" centres, including hospitals and water systems.

By Sunday afternoon, power had been restored to about half of Havana, according to its electricity company.

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.

The Communist-run country has an ageing electricity infrastructure and chronic fuel shortages.

A coalition of international socialist groups arrived in Havana over the weekend to show their support for the Cuban government, bringing with them aid donations of solar panels, basic food kits and medicines.

The "Nuestra America" convoy, a flotilla of aid leaving Mexico, was delayed because of rough sea conditions but is expected to arrive in Havana's port on Monday.

Rare public dissent sparked by the recent crisis and national power cuts saw locals banging pots and pans in central Havana on Monday. Protesters in central Cuba's town of Morón also attacked and set fire to the Communist Party headquarters on the same day.

Unauthorised demonstrations are illegal in Cuba and those who defy the ban risk being jailed.

"The circumstances are really bad," one man in Havana told the BBC. "There are political and economical issues, crisis of all sorts, economic, social. It's been going on for decades and the problems are pilling up."

Another woman said: "There's nowhere to live, nowhere to run to. Young and older people don't have work. Everything has slipped away little by little."

Since US soldiers seized former Venezuelan President Nicolás Maduro on 3 January, Donald Trump has been repeatedly asked about similar mooted plans for Cuba.

President Trump is reported to want the removal of Cuba's President Miguel Díaz-Canel, a regional ally of Venezuela, as a condition of lifting the fuel embargo.

Last week, Trump suggested there could be a "friendly takeover" of Cuba, later remarking it would be an "honour".

Speaking to campaigners delivering humanitarian supplies this weekend, the Cuban president said the island has a "preparation plan to raise our people's readiness for defence" against any US military aggression.

The American and Cuban governments have held initial phases of bilateral talks aimed at ending the crisis, Díaz-Canel has confirmed, although it is unclear how they are progressing.

On Friday, Cuban Deputy Foreign Minister Carlos Fernandez de Cossio insisted that "the political system of Cuba is not up for negotiation, and of course, neither the president nor the position of any official in Cuba is subject to negotiation with the United States", Reuters reported.