Tensions between Angola's president and his long-serving predecessor have erupted into the open as an anti-corruption drive targets the former ruler's family.

Former Angolan leader Jose Eduardo dos Santos said Friday he will quit as head of the governing party by 2019 after the ruling MPLA denied tensions with his successor, President Joao Lourenco.

Angola's state oil company has announced an investigation into "possible misappropriation" of funds by Isabel dos Santos, the daughter of the former president, during her time as the company's chief executive.

Angolan President Joao Lourenco on Wednesday fired his predecessor's daughter from her influential post as head of the Sonangol state oil company, the presidency said in a statement.

Jose Eduardo dos Santos's 38-year reign over Angola finally came to an end Tuesday when his hand-picked successor Joao Lourenco was inaugurated as president at a ceremony in Luanda.

Angola’s ruling MPLA party has won a general election by taking 61.07 percent of the vote, the electoral commission said on Wednesday, making João Lourenço the next president of sub-Saharan Africa’s third-largest economy.

Dos Santos, 75, who has ruled since 1979 and is reportedly in poor health, will hand over to former defence minister Joao Lourenco at the presidential inauguration on September 25.

Angola's election commission on Monday rejected accusations of irregularities in last month's vote which saw the MPLA party, which has ruled since 1975, retain power.

Four opposition parties in Angola on Sunday called for a recount in last month's general election, alleging "irregularities" during the vote that kept the ruling party in power.

Angola's ruling MPLA won this week's election, a poll official announced Thursday, with party candidate Joao Lourenco now set to succeed President Jose Eduardo Dos Santos who has ruled for 38 years.

When Angolan President Jose Eduardo dos Santos steps down and his successor is chosen in Wednesday's elections, it will bring to an end a 38-year reign dominated by his unrelenting authoritarian style.

Angola goes to the polls Wednesday in a historic election marking the end of President Jose Eduardo Dos Santos's 38-year reign, with his party set to retain power despite the country's economic crisis.