The number of people arrested during a corruption inquiry into Venezuela’s state oil company over unpaid oil cargoes has risen to 34, according to the country’s attorney general.

Tarek Saab said that the most recent arrests are the latest chapter of an anti-corruption drive started in 2017 against a “mafia” that become rooted within Petroleos de Venezuela SA (PDVSA) that sought to “embezzle the nation”.

Saab declined to say if former minister Tareck El Aissami was under investigation, according to Reuters. A long-time ally of President Nicolas Maduro, Aissami quit the role in March and promised to support the inquiry into alleged illicit payments connected to oil exports.

He was replaced by Pedro Rafael Tellechea who was only appointed as head of PDVSA this year.

As PDVSA boss, he announced an audit into oil supply contracts owing to huge losses after tankers left the country without proper payments being made. Reuters reported that the PDVSA had accumulated some $21.2bn in unpaid bills.

Venezuela — which is sitting on the world’s largest oil reserves — has been forced to turn to intermediaries and the dark fleet to move its cargoes because of US sanctions imposed on PDVSA in 2019.

A series of arrests have been made in recent weeks with 51 people detained overall in connection with various corruption cases related to other companies.

“We have done serious, methodical, detailed work, which has led us to these conclusions,” said Saab in a statement. “No one should be surprised."

Saab also repeated long-standing demands for the extradition of four senior officials, including another former oil minister and a head of security of PDVSA, over corruption claims from Spain, Italy and the US.

Rafael Ramirez, who served as both oil minister and head of PDVSA, fell out with the Maduro government in 2017. Since then, the government has unsuccessfully pursued his extradition from Italy.