Isabel Dos Santos appeared in Forbes 2016 as Africa’s richest woman.
According to Forbes, Dos Santos real time Net Worth as of December 20, 2017 was $3 billion.
Last September, Angolan President Joao Lourenco discharged Santos as chair of the state oil company Sonangol.
Today, the oil giant has announced investigation into “possible misappropriation” of funds by the daughter of Angola’s longtime former president.
"We have established an internal commission of inquiry to investigate the information published," Sonangol spokesman Mateus Benza said on Tuesday.
"We are verifying possible misappropriation, but I can't yet confirm anything," AFP reported.
Dos Santos was appointed head of the oil firm by her father in 2016. Dismissing criticism of her appointment, she told BBC Focus on Africa radio, that the key reason for the appointment was due to her background in the business sector and a “track record of building business."
According to the Novo Jornal and the Jornal Economico, the new leadership at Sonangol had identified a suspect transfer of 57 million euros ($67 million) to Dubai.
Forbes quotes Dos Santos’ assets in Angola to include 25% of Unitel, the country's largest mobile phone network, and 42% of a bank, Banco BIC.
Additionally, she owns nearly 6% of oil and gas firm Galp Energia (alongside Portuguese billionaire Americo Amorim) in Portugal. She is also a controlling shareholder of Portuguese cable TV and telecom firm Nos SGPS (formerly called Zon). In October 2015, four members of the European Parliament publicly called for an investigation into her investments in Portugal, questioning their legality.
In response to the allegations, Dos Santos took to social media terming it a “campaign of defamation”.
"This fake news... doesn't deserve any credibility since their only goal is to cast doubt on the integrity of Isabel dos Santos," she said in a tweet.
Prosecutors in the capital Luanda told AFP on Tuesday evening that they had not received a formal complaint.
President Lourenco has promised to fight against corruption in the country.