Nigeria's president has fired a slew of secretaries who have run the government for months in a sign he will install a streamlined, long-awaited Cabinet.

A statement from the presidency Tuesday said it would retain only 25 secretaries of at least 40.

Secretaries have been managing the ministries since President Muhammadu Buhari took office in May. He said he needed time to assemble the right team to combat corruption that keeps most people impoverished in Africa's biggest oil producer.

Politicians privy to negotiations say Buhari's Cabinet will include only 25 ministries. They requested anonymity because the matter is sensitive.

The Cabinet is expected to be sworn in Wednesday.

Many others have already been sacked, including the head of Nigeria's anti-corruption agency, on Monday.