Portuguese bank EuroBic said it will stop doing business with companies and people linked to its main shareholder Isabel dos Santos after an investigation accused the billionaire daughter of Angola’s former ruler of murky dealings.

The International Consortium of Investigative Journalists this week accused Dos Santos, who is reputed to be Africa’s richest woman, of using “unscrupulous deals” to build her fortune, estimated at $2 billion. She has denied any wrongdoing.

The allegations were based on more than 715,000 confidential financial and business records provided by the Platform to Protect Whistleblowers in Africa, an advocacy group based in Paris, as well as hundreds of interviews. The cache of documents is known as Luanda Leaks, named for Angola’s capital, Luanda.

Dos Santos owns a 42.5% share of EuroBic, based in the Portuguese capital Lisbon, and is believed to have used it to move funds internationally. The bank has assets of around 7.8 billion euros ($8.6 billion).

EuroBic’s board said in a statement late Monday it is cutting ties with Dos Santos’ companies and people close to her and is undertaking an immediate audit.

It said the moves are due to “the public perception that this bank might not be complying with the rules because Isabel dos Santos is one of its principal shareholders.”

Portugal’s central bank said it wants to review EuroBic’s financial operations, including its procedures to prevent money-laundering. The Bank of Portugal said it had been closely monitoring EuroBic’s operations in recent years.

Jose Eduardo dos Santos, Isabel’s father, ruled oil- and diamond-rich Angola for 38 years until 2017. Human rights groups have long accused the former president of stealing vast amounts of state money during his rule. Before stepping down, he appointed his daughter head of the state oil company, Sonangol.

Last December, a Luanda court froze Isabel dos Santos’ major assets, which include banks and a telecom company. The government says it is trying to recover $1.1 billion it says the country is owed by Dos Santos, her husband and a close associate of the couple.

Angola’s minister for economic coordination, Manuel Jose Nunes Junior, said in a speech at Chatham House in London on Tuesday that his country is trying to crack down on corruption.

“After a six-month grace period, when assets taken illegally from (Angola) could have been brought back without any penalties, the state is now (taking) all judicial, legal and diplomatic and other measures available to ensure the repatriation of those resources and ensure the recovery of assets to national soil,” he said.

Dos Santos says the legal action against her is a “witch hunt” launched by officials who replaced her father.