The US has criticized the Venezuelan government over the death of an opposition figure in custody, calling it a reminder of the vile nature of President Nicolás Maduro's regime.

Alfredo Díaz died in his prison cell at the El Helicoide prison in Caracas where he was being held for more than a year, human rights organisations and opposition groups have said.

The Venezuelan government stated that Díaz, 56, showed signs of a heart attack and was taken to hospital, where he died on Saturday.

The US intervention is the latest in an escalating war of words between the Trump administration and Maduro, who has accused it of seeking regime change.

In recent months, the US has increased its military presence in the region and has carried out a series of deadly strikes on boats used for smuggling drugs.

US President Donald Trump accused Maduro of being the head of one of the region's drug cartels - a claim Maduro vehemently denies - and threatened military action by land.

The US State Department's Bureau of Western Hemisphere Affairs stated that Díaz had been arbitrarily detained in a torture centre.

Díaz was detained in 2024 after disputing the results of that year's presidential election, which the government-controlled election council declared Maduro the winner despite opposition tallies showing otherwise.

The elections have been widely dismissed as neither free nor fair, sparking national protests.

Díaz, a former governor of Nueva Esparta, was accused of incitement to hatred and terrorism for contesting Maduro's victory.

Venezuelan human rights group Foro Penal has expressed concern over the deteriorating conditions for political prisoners in the country. Alfredo Romero, its president, highlighted that Díaz's solitary confinement resulted in a lack of meaningful contact, with only one visit from his daughter during his incarceration.

María Corina Machado, a prominent opposition leader awarded this year's Nobel Peace Prize but currently in hiding, stated that Díaz's death was part of a troubling trend of political prisoner deaths amidst post-election repression.

The Democratic Unitary Platform and Díaz's own party, Democratic Action (AD), have condemned the circumstances of his death, demanding accountability from the Venezuelan government.

As tensions mount between the US and Venezuela, the Maduro government has fortressed its military strength while simultaneously renewing agreements with international allies.