The first major scalp claimed by Angola's new president Joao Lourenco in his war on corruption and nepotism was that of his predecessor's daughter, who was sacked as head of the state oil company.

The next big name linked to former president Jose Eduardo dos Santos was that of his son, Jose Filomeno, who was removed from his post at the top of the African nation's $5 billion sovereign wealth fund.Quick work for a president with barely 100 days on the job.

Lourenco's manoeuvering against the nepotistical vestiges of Angola's last president began in earnest in November with the toppling of Isabel dos Santos -- said by Forbes to be Africa's richest woman.

The shake-up at the Sonangol oil giant marked a watershed moment in Lourenco's young presidency as he sought to assert his authority and clear out the legacy of his controversial predecessor.

During his presidential campaign, the former defence minister vowed to distance himself from Dos Santos who remains head of the ruling People's Movement for the Liberation of Angola (MPLA) party.

Just a month after Isabel dos Santos was fired, Sonangol announced it was opening an investigation into "possible misappropriation" of funds during her time as chief executive.

Angolan media outlets have accused her of ordering suspect transfers and payments worth tens of millions of dollars.

But although her sacking caught some Angola watchers off-guard, Lourenco's dismissal this week of Jose Filomeno as head of the oil-rich country's vast wealth fund did not.

Lourenco, 63, had hinted he might sack Filomeno during a speech to mark his first 100 days in office after winning August's election on an anti-graft, reformist platform.

- Sidelined -

"Lourenco has sidelined all of those over whom he doesn't have control," said Benjamin Auge, an analyst at the French Institute of International Relations (IFRI).

"The members of the Dos Santos family fall into this category, which is why they've been cast-off, one by one."

Like his sister, Jose Filomeno was the embodiment of the political-financial empire built by their father that funnelled the nation's wealth to friends and relatives of the all-powerful Dos Santos clan.

But the new sheriff in town appears determined to end the family's grip on the nation's purse strings.

"No one is above the law," Lourenco said before being sworn in.

For weeks now, Angolan media have been running stories alleging corruption by the Dos Santos family, which had previously been seen as untouchable.

As well as the corruption probe facing Isabel, her half-brother was implicated in the "Panama Papers" scandal which showed how the world's wealthy shift profits around the globe to drastically cut tax.

Also this week, state television revealed the lavish terms of a government contract awarded to another of Dos Santos' daughters, Welwitschia.

- 'Might dig his feet in' -

Facing official scrutiny is proving to be an uncomfortable new experience for the former first family.

Isabel has huffily denied the allegations against her and accused her critics of a "campaign of defamation" and "fake news".

And even Dos Santos himself waded in, admitting in a rare public appearance last month that while "the changes are necessary, they should not be so radical".

Angola's opposition has been quick to praise the government's campaign against "nepotism" -- an issue it has long campaigned about, urging Lourenco see the process through to the end.

"All of these sackings will be irrelevant if they aren't followed by legal action," said Lindo Bernardo Tito, vice president of the Casa-CE party.

"The president should order judicial inquiries without delay."

- Personal crusade? -

Few observers thought that Lourenco would push his fight against nepotism and corruption as far as he has.

"I don't imagine any serious case will emerge against the family (although) the Sonangol probe is clearly a warning of what could happen," said Alex Vines, an analyst at Britain's Chatham House think-tank.

Keen to keep the peace with his one-time mentor, Lourenco has denied any kind of "vendetta" against the Dos Santos family.

"I don't see any tension in our relations," he said on Monday. "We are not persecuting them."

But Vines said the new president needed to be cautious.

"Lourenco does need to now prove he is not personalising this -- and allow an up-to-now exemplary transition to continue to be smooth," added Vines.

"Dos Santos had planned to step down from the MPLA presidency in 2018 -- but if he senses there is a witch hunt again his family and friends, he might dig his feet in."