A court under the administration of Angolan President Joao Lourenço has ordered the assets and banks account of Isabel dos Santos to be frozen, BBC reports.

The daughter of former president José Eduardo dos Santos has been dubbed the richest woman in Africa due to her billionaire status (Forbes notes she's estimated to have a fortune of $2.2 billion). However, due to the current administration's effort to clean up corruption, Angola is looking to reclaim $1 billion that Isabel dos Santos and her associates allegedly owe—which she has vehemently denied during her father's time in office.

DW adds that the court will be looking into inconsistencies involving state-run companies including oil company Sonangol and diamond-marketing firm Sodiam. "The state through its companies...transferred enormous quantities of foreign currency to companies abroad whose beneficiaries are the defendants, without receiving the agreed return," the court order states. "The defendants recognize the existence of the debt but allege that they do not have the means to pay."

The other assets included in this order that have been seized and frozen include her stake in telecoms company Unitel and bank Fomento de Angola (BFA). Isabel dos Santos currently oversees a big business empire with stakes in Portuguese and Angolan companies, including cable TV outlet Nos SGPS. She chooses to lives abroad as she says she fears for her safety in Angola.

Brother José Filomeno dos Santos is also currently on trial facing corruption charges.

"I would like to leave a message of tranquility and confidence to my teams," she says in a statement on Twitter Monday. "We will continue, every day, in every business, doing our best and fighting for what I believe in for Angola. The road is long, the truth will prevail. United we stand stronger."

All eyes were on the daughter of the former president in 2016 when he selected her to be the head of Sonangol. This appointment was met with controversy, where Lourenço dismissed her from the role a year after her father handpicked him to be his successor.