(Reuters) - Venezuelan former oil minister Nelson Martinez, who was arrested in 2017 as part of a sweeping graft probe at state-run oil company PDVSA, has died in state custody, five people familiar with the matter said on Wednesday.
Martinez, a chemist who also ran PDVSA and its U.S. subsidiary Citgo Petroleum, had been transferred to a military hospital from prison because of kidney problems, according to two of the sources. He had a heart attack while receiving dialysis, they said.
Martinez was jailed after the country's top prosecutor said he allowed a poor refinancing deal for Citgo to go ahead without government approval. He was arrested alongside Eulogio del Pino, another former oil minister and PDVSA president, who remains jailed.
Martinez's death will likely fuel debate over the conditions of imprisoned former politicians and government officials, who in recent years have increasingly included former top leaders whom President Nicolas Maduro has accused of wrongdoing.
His death comes two months after a nationwide scandal over the death of a municipal legislator, Fernando Alban, who the government says committed suicide but who opposition leaders insist was murdered in prison.
"The death of Nelson Martinez is the responsibility of Nicolas Maduro, who...held him hostage for a year knowing he was ill," Rafael Ramirez, a fugitive oil minister and PDVSA president under late President Hugo Chavez who is wanted on corruption charges, wrote on Twitter.
The opposition to Maduro's socialist government, which has overseen a collapse of the OPEC nation's economy, dismisses the probe as an internal power struggle within Maduro's inner circle, noting that the industry has been under tight control of the ruling Socialist Party since early in Chavez's 14-year rule.
Neither the Information Ministry, the Oil Ministry nor PDVSA responded to emails seeking comment.
Chief Prosecutor Tarek Saab, who announced Martinez's arrest in a televised speech in November 2017, declined to comment when reached by telephone.
Martinez had yet to appear before a judge at the time of his death, and the date for his preliminary hearing was pushed back several times, two of the people said. His lawyers began asking authorities months ago for Martinez to be granted house arrest, citing his ill health, one of the people said.
Martinez started having health problems while leading Citgo, based in Houston. Maduro named him oil minister in January 2017, and he assumed the dual role of PDVSA president later that year, replacing del Pino.
He had joined PDVSA in 1980 and oversaw the company's offices in London, Argentina and Ecuador before being tapped to lead Citgo.
(Reporting by Deisy Buitrago, Alexandra Ulmer and Marianna Parraga; Writing by Luc Cohen and Brian Ellsworth; Editing by Peter Cooney and Leslie Adler)