The eldest daughter of former Angolan President José Eduardo dos Santos has been sacked as chair of the board of the state-owned oil firm Sonangol.
A presidential decree on Wednesday said Ms Isabel dos Santos had been replaced by Mr Carlos Saturnino.
Ms dos Santos was appointed to chair the Sonangol board of directors by her father in June 2016.
She was tasked with the responsibility of ensuring the restructuring of the state company.
New President João Lourenço took over from dos Santos in August, following an election, marking the end of a 38-year reign.
His sacking of the predecessor's daughter is seen as a powerful message asserting his authority.
Earlier this month, Ms Isabel dos Santos was ranked by Forbes magazine the 74th most powerful woman globally in 2017.
The publication also ranks her Africa's richest woman.
The Forbes 100 Most Powerful Women list names prominent personalities, with remarkable impact in fields such as politics, philanthropy, technology, automotive, finance and investments.
Ms Isabel dos Santos's net worth, according to Forbes, is $3 billion.
The 44-year-old studied engineering at King’s College, London, and opened her first business, a restaurant called Miami Beach in Luanda, in 1997 when she was 24.
Her assets in Angola include a 25 per cent stake in Unitel, one of the southern Africa state’s two mobile phone networks, and a 25 per cent stake in Banco Internacional de Credito (Banco BIC).
Her representatives deny that her holdings have any connection with her father.
According to Forbes magazine, the dos Santos family controls a huge chunk of Angola’s economy.