Angola last year posted strong growth but investment rates remain very low, the World Bank said on Thursday, as it praised Africa's second oil producer for improved transparency.
A combination of high oil prices and rising production boosted the country's GDP growth and greatly increased fiscal revenues.
"In 2012 the government's fiscal position strengthened, inflation declined to single digits, and international reserves continued to accumulate," the Bank said in a report.
It said the oil sector last year grew by 5.2 percent on the back of rising oil prices.
But investment levels are "very low", hovering around 13 percent of GDP, which is "well below the three-year average for Sub-Saharan Africa of 24 percent," said Bank.
The Bank lauded Angola for boosting transparency in state finances and crude sales.
"The authorities have made significant strides in improving the transparency and accountability of public financial management, but challenges remain.
"The government has improved collection and reporting processes for oil revenues and transfers, which is expected to enhance transparency and accountability in oil sector management."
Corruption has been rampant in the oil-rich southern African state, which ranked 157 of 174 countries in Transparency International's corruption perception index last year.
The Bank said the recently established sovereign wealth fund "could do much to stabilize expenditures against oil-price volatility" and help build long-term savings in anticipation of the eventual decline of the oil sector.
Angola last year reported a GDP growth rate of 8.1 percent , but that was forecast to ease to 7.2 percent this year.
The country which ranks as Africa's second largest crude producer after Nigeria, has reported an average 10 percent growth rate over the last decade.
Despite the massive oil wealth which has seen some of the fastest growth in the world, large-scale misappropriation of public funds means the majority of the people in the country remain very poor.