FILE PHOTO: Isabel Dos Santos, daughter of Angola’s former President and Africa's richest woman, sits for a portrait during a Reuters interview in London, Britain, January 9, 2020. REUTERS/Toby Melville/File Photo

FRANKFURT (Reuters) - The euro zone’s top bank supervisor blamed a “mess” of diverging laws across the bloc on Tuesday for the European Central Bank’s failure to stop Angolan billionaire Isabel dos Santos, who is suspected of fraud, from controlling a bank in Portugal.

“I’m not very happy to be honest, not about the performance -- our or Banco de Portugal’s performance -- I’m nor very happy about the ... mess in the legislative set-up here,” Andrea Enria told a news conference when asked about Dos Santos.

“It’s very difficult for us to do a fit-and-proper assessment in a proper way. It’s an area that is one of the least harmonized.”

Dos Santos, the eldest child of Angola’s former president Jose Eduardo dos Santos, has been named a formal suspect over allegations of mismanagement and misappropriation of funds during her time as chairwoman of state oil company Sonangol.

She denies any wrongdoing but announced plans last week to sell its controlling stake in Eurobic after Portugal’s market watchdog opened inquiries into various firms in which she holds stakes.