Venezuela's ex-oil minister and ex-PDVSA head arrested
Two powerful Venezuelan former oil officials have been arrested as part of a sweeping anti-corruption operation.
A number of senior officials at Citgo, Venezuela's US-based refining company were detained last week.
Critics of President Nicolás Maduro say this is part of a political purge.
They say Mr Maduro, who is expected to stand for re-election in presidential elections due to be held next year, is sidelining influential and capable figures within his party who he thinks could become rivals for the presidency.
Venezuela's oil industry is key for the government as it accounts for about 95% of the country's export earnings.
But falling oil prices have seen earnings fall steeply and international credit ratings agencies declared PDVSA in default earlier this month.
Critics of the Maduro government say the crisis in the country's oil industry is largely down to mismanagement and lack of investment.
But the government has long maintained that it is the victim of an "economic war" waged against it by "imperialist forces".
More recently, however, government officials have shifted the blame on to "corrupt officials".
Chief prosecutor Tarek William Saab said in a news conference that Mr Del Pino was suspected of playing a part in a $500m (£370m) corruption scheme at Petrozamora, a joint venture between PDVSA and Gazprom.
He also said that Mr Martínez had been detained for allegedly allowing a Citgo refinancing deal to proceed without the approval of the Venezuelan government.
The chief prosecutor said the operation had been led by Venezuela's military counterintelligence unit.