Jose Filomeno dos Santos planned to siphon off $1.5bn when he ran Luanda’s sovereign wealth fund, government says.

The son of Angola’s former president, Jose Eduardo dos Santos, planned to siphon off $1.5bn when he ran the oil-rich country’s sovereign wealth fund, the finance ministry said.

Jose Filomeno dos Santos, nicknamed “Zenu”, is accused of “fraud, misappropriation of funds, money laundering and associating with criminals”.

The $1.5bn figure is three times the sum he was initially accused of illegally transferring to a British bank.

The finance ministry said that Filomeno dos Santos disguised the transfer as a project aimed at attracting investment in Angola with the help of a fake guarantee from Credit Suisse.

The Swiss bank told AFP news agency that “documents had been forged” and that it had not received “any money relating to this case”.

The finance ministry said $500m had been transferred to a London bank and that Angola was supposed to make two more such payments.

The first transfer was blocked by UK authorities who suspected foul play.

Filomeno dos Santos was appointed to head the $5bn oil-fuelled sovereign fund by his father in 2013 but was sacked by President Joao Lourenco, who took power in January this year.

Former central bank governor Valter Filipe da Silva, who has been charged alongside Filomeno dos Santos, has promised to “cooperate” with the authorities.

Filomeno’s half-sister, Isabel dos Santos, was also sacked from her job as the head of state-owned oil giant Sonangol. Thought to be Africa’s richest woman, she has denied all allegations against her.

Jose Eduardo dos Santos ruled Angola for 38 years with an iron grip. During his regime, he was accused of running the country’s economy to enrich himself and those around him.