Nuno Ribeiro da Cunha died on Wednesday, and his death was reported on Thursday soon after Angolan prosecutors named both as suspects. Documents leaked this week alleged Isabel dos Santos, who is the daughter of ex-president Jose Eduardo dos Santos, plundered state coffers to build her fortune, estimated at $2.1 billion.

EuroBic said it would end its business relationship with her, as she is reportedly the bank's main shareholder through two companies she owns. Investigations into Isabel dos Santos's 18-month tenure as Sonangol head from June 2016 were opened after her successor Carlos Saturnino raised the alarm about "irregular money transfers" and other dodgy procedures.

It was later reported as saying that she was selling her capital stake in the bank. The bank added that it would investigate transfers worth tens of millions of dollars she had made. Some of the transfers drained Sonangol's account at EuroBic. In a statement on Thursday, she described the allegations against her as "extremely misleading and untrue".

Named Africa's richest woman, Isabel dos Santos is accused of using her father's backing to plunder state funds from the oil-rich but poor southern African country and moving the money abroad with the help of Western firms.