Venezuela is to set up a formal inquiry into suspicions that the late President Hugo Chavez's cancer was the result of poisoning by his enemies abroad, the government said last night.
The accusation has been derided by critics of the government.
They view it as a conspiracy theory intended to feed fears of "imperialist" threats to Venezuela's socialist system and distract people from daily problems.
However, acting President Nicolas Maduro vowed to push through a serious investigation into the claim, which was first raised by Mr Chavez himself after he was diagnosed with the disease in 2011.
"We will seek the truth," Mr Maduro told regional TV network Telesur late last night.
"We have the intuition that our commander Chavez was poisoned by dark forces that wanted him out of the way."
Foreign scientists will be invited to join a government commission, the OPEC nation's acting leader said.
Mr Maduro, 50, is Chavez's handpicked successor and is running as the government's candidate in a snap presidential election on 14 April that was triggered by Mr Chavez’s death last week.
He is trying to keep voters' attention firmly focused on Mr Chavez to benefit from the outpouring of grief among his millions of supporters.
The opposition is centring its campaign on portraying Mr Maduro, a former bus driver, as an incompetent who, they say, is morbidly exploiting Mr Chavez's demise.
Running for the opposition's Democratic Unity coalition is a business-friendly state governor, Henrique Capriles, 40, who lost to Mr Chavez in a presidential vote last year.
Today is the last day of official mourning for Mr Chavez, although ceremonies appear set to continue.
His embalmed body was to be taken in procession to a military museum on Friday.
Millions have filed past his coffin to pay homage to a man who was adored by many of the poor for his humble roots and welfare policies, but was also hated by many people for his authoritarian style and bullying of opponents.
Though Mr Maduro has spoken about combating crime and extending development programmes in the slums, he has mostly used his frequent appearances on state TV to talk about Mr Chavez.
The 58-year-old president was diagnosed with cancer in his pelvic region in June 2011 and underwent four surgeries before dying of what sources said was metastasis in the lungs.
Mr Maduro said it was too early to specifically point a finger over Mr Chavez's cancer, but noted that the United States had laboratories with experience in producing diseases.
"He had a cancer that broke all norms," Mr Maduro told Telesur.
"Everything seems to indicate that they affected his health using the most advanced techniques ... He had that intuition from the beginning."
Mr Maduro has compared his suspicions over Mr Chavez's death with allegations that Palestinian leader Yasser Arafat died in 2004 from poisoning by Israeli agents.
The case echoes Mr Chavez's long campaign to convince the world that his idol and Venezuela's independence hero Simon Bolivar died of poisoning by his enemies in Colombia in 1830.
Polls from before Mr Chavez's death gave Mr Maduro a lead over Mr Capriles of more than ten percentage points.