Ramirez himself placed the blame for the late president’s recent death – which came after a cancer battle – with the US and Israel, according to BBC report.
Chavez died over a week ago with his funeral held last Friday in the capital of the major Opec nation, Caracas.
His death followed prolonged treatment for cancer in Cuba, but Venezuelan authorities have for some time made unsubstantiated claims that outside forces were responsible for his illness.
The BBC reported on Wednesday that Ramirez had promised the establishment of the inquiry which he hoped would provide evidence that Chavez was killed.
In an interview with the UK broadcaster’s Latin American service BBC Mundo, Ramirez likened Chavez’s death to that of former Palestinian leader Yasser Arafat who died in 2004 after being confined to his compound by Israeli forces. His remains were exhumed last year as part of a murder inquiry.
Relations between Venezuela and the US have hardened further since Chavez’s death with each country expelling either military attaches or diplomats.
Acting leader Nicolas Maduro has vowed to continue Chavez’s socialist legacy should he be reelected in a snap election to be held within a month.