Nigeria's anti-corruption agency has recovered $28.88-million after launching an investigation into alleged fraud at a government ministry responsible for tackling poverty, a spokesperson said.

Betta Edu, the Minister of Humanitarian Affairs and Poverty Alleviation, was suspended in January less than six months after her appointment by President Bola Tinubu, who came to power last year on a promise to revive growth and fight corruption.

Economic and Financial Crimes Commission (EFCC) spokesperson Dele Oyewale said in a statement that the probe, ordered by the president, had uncovered a "system and intricate web of fraudulent practices".

So far, 32.7-billion naira ($28.43-million) and $445 000 had been recovered during the investigation into the activities of past and suspended ministry officials, he said.

"Investigations are ongoing and advancing steadily," Oyewale said.

The EFCC is also examining the potential misuse of Covid-19 funds, a World Bank loan, and loot recovered from former dictator Sani Abacha which was allocated to the ministry for poverty alleviation programs in Africa's most populous country.

The investigation extends beyond individuals, implicating banks that allegedly facilitated the fraud, he said.

"Banks involved in the alleged fraud are being investigated. Managing directors of the indicted banks have made useful statements to investigators digging into the infractions," Oyewale said, without providing details of the banks.

Nigeria has struggled for decades with endemic corruption among senior public officials. Despite being Africa's top oil producer and biggest economy, the country suffers widespread poverty, which many Nigerians blame on the political elite.