Venezuela's oil minister Tareck El Aissami resigned on Monday after prosecutors opened a corruption investigation into officials at the state oil company PDVSA.
Anti-corruption police on Sunday arrested two people closely linked to El Aissami: top PDVSA official Antonio Pérez Suárez, and Joselit Ramírez, who manages oil industry funds through cryptocurrencies.
"Given the investigations that have begun into the serious acts of corruption in PDVSA, I have taken the decision to submit my resignation as oil minister with the aim of totally supporting, accompanying and backing this process," El Aissami wrote on Twitter.
El Aissami, who had been in the position since April 2020, added that he supported the government's "crusade" against corruption.
Authorities have been probing high-ranking officials "who could be involved in serious acts of corruption and embezzlement", the national police force said.
Legislator Hugbel Roa was among those detained, alongside a prominent lawyer, an anti-terrorism judge and a mayor.
It is not the first investigation into graft at the state oil company.
Former oil ministers Eulogio Del Pino and Nelson Martínez, who died while in police custody, were previously arrested as part of a corruption investigation.
President Nicolás Maduro said he had "decided to accept the resignation to facilitate the investigations that should result in the establishment of the truth, and the punishment of the culprits."
El Aissami, who is under US sanction, is one of the most powerful leaders of the ruling Socialist Party of Venezuela. He had previously served as vice president, as well as minister of the interior and industry.
The newspaper Ultimas Noticias, which is close to the ruling party, reported that Ramírez diverted some US$3 billion from last year's oil sales that were conducted in cryptocurrencies to circumvent US sanctions against Venezuelan crude.
The firm Ecoanálitica estimated that the foreign currency income of the Venezuelan state in 2022 totalled US$25 billion, said company director Adrubal Oliveros.
"For us to understand the magnitude of the embezzlement of US$3 billion dollars," Oliveros said, "what disappeared is equivalent to 12 percent of last year's revenue."