JOHANNESBURG (AP) — Angola's new leader has removed the daughter of former President Jose Eduardo dos Santos as chair of the state-owned oil company, the government announced Wednesday, in a surprise move that appeared to assert independence from one of Africa's longest-ruling families.

President Joao Lourenco removed Isabel dos Santos as chair of the board of directors of Sonangol and replaced her with Carlos Saturnino, secretary of state for oil, local news outlet Angop reported, citing a statement from the presidency.

Isabel dos Santos has been reported to be Africa's richest woman. Her father appointed her about 18 months ago to head Sonangol, where she led an efficiency drive after the continent's third-largest economy was rocked by low commodity prices.

Angola vies with Nigeria as Africa's top oil producer, with companies such as Chevron, ExxonMobil and BP pumping from deep-water offshore wells. The country has long been plagued by corruption and a deep divide between rich and poor.

"The firing of Isabel dos Santos from Sonangol is a powerful signal that Lourenco will not tolerate the continuation of his predecessor's influence and meddling in the political economy," Markus Weimer, founder of London-based Faktor Consultants, said in an email. "The economic and financial crisis in Angola is biting hard, and if Lourenco remains associated with the excesses of dos Santos he will suffer politically.

"In the best case, this can lead to better governance and reforms which are in the public interest, while there's also the risk that the new elite simply replaces the outgoing one at the top of the table."

Lourenco also removed seven other Sonangol board members and appointed eight replacements, Angop reported.

He won election In August after the elder dos Santos stepped down from a rule that began in 1979. The former defense minister has been expected to largely follow dos Santos' lead.

Isabel dos Santos also has interests in mobile phones and banks across Angola and former colonial ruler Portugal.