The oil-rich central African state of Gabon has carried out a string of top-level arrests and reassignments as it ramps up a drive against corruption.

Nearly two dozen people, some of them in the inner circle of power, have been ousted from office, arrested or given other duties.

A leading figure is President Ali Bongo Ondimba's chief of staff, Brice Laccruche Alihanga, who has been dismissed from his job. He was sacked as minister late on Monday, Prime Minister Julien Nkoghe Bekale said in a video message.

"The president decided to act fast," the prime minister said.

Others are former director of the National Fund for Health Insurance Renaud Allogho Akoue and the head of presidential communications, Ike Ngouoni, who was regarded as Laccruche's right-hand man. Both have been arrested.

Key changes have also been made in the intelligence and security forces, under decisions carried out by the president's office.

What's the background?

The pro-government daily L'Union reported that more than 85 billion CFA francs (142 million U.S. dollars) had disappeared from the funds of the Gabon Oil Company (GOC) over the past two years. 

GOC is a state firm run by Patrichi Tanasa, who is close to Laccruche. Tanasa has been in custody since late November.

An investigation by L'Union also targeted the Dupont Consulting Company, whose executives included Laccruche's brother Gregory Laccruche, a businessman and mayor of Akanda, a coastal town northwest of Libreville.

Gregory Laccruche was detained on Wednesday, a source close to the presidency told AFP.

The public prosecutor said that suspects have been charged with embezzlement and money laundering.

"This is a political vendetta," declared Boris Rosenthal, aide to detained presidential spokesman Ngouoni.

Bongo's office said the inquiry has no political link.

(With input from AFP)