Angolan president Jose Eduardo dos Santos may have to answer questions concerning his daughter’s recent appointment as the head of state-owned Sonangol.

According to court documents seen by Reuters, Angola’s Supreme Court has asked dos Santos to respond to an inquiry into why he appointed Isabel dos Santos as CEO of the state-owned oil firm in June.

The court’s request was made in response to a case filed by just over a dozen Angolan lawyers earlier this year accusing the president of nepotism and violating Angola’s probity law, Reuters said.

President dos Santos has a week to respond to the request, a report by Quartz said.. Neither the president nor his daughter have commented on the matter.

Isabel dos Santos is currently listed as the richest woman in Africa by Fortune and is reportedly worth $3.2 billion.

Isabel has promised to improve efficiency at Sonangol and boost margins to help the firm cope with low oil prices.

Earlier this year, Sonangol backed out of a proposed purchase of stakes in two Angola blocks from Cobalt Energy.

Cobalt said in August it received a letter from Isabel dos Santos confirming Sonangol’s support of marketing and selling the stakes to a third party.

Angola has overtaken Nigeria as the largest oil producer in Africa as waves of militant attacks against Nigeria energy infrastructure disrupt production.

According to the U.S. Energy Information Administration, Angola produced nearly 1.8 million barrels per day of crude oil last year.