International rights group, Human Rights Watch (HRW) called on the government of Angola to explain how $32 billion, or more than a quarter of the country's GDP, disappeared from government funds in three years.
The finding was first published in the December 2011 report by the International Monetary Fund (IMF), which says that the funds were spent or transferred in 2007-2010 without being properly documented in the budget.
"Tens of billions of dollars could be used for the benefit of the Angolan people - instead the government can't account for them," HRW business and human rights director Arvind Ganesan said.
"Angola's government has taken credit for improving transparency over its oil revenues and auditing the state oil company, but the disappearance of $32 billion raises serious questions about its efforts and underscores the need for public accountability," he went on.
The IMF website puts the estimated Angolan GDP in 2011 at $99.3 billion in current prices and at $116 billion if based on purchasing-power-parity (PPP) valuation.