Bunyoni, who previously served as the country’s police chief and security minister, was removed from office last September in the first significant government reshuffle since President Evariste Ndayishimiye took office in 2020.
Police and intelligence officers reportedly searched three of Bunyoni’s properties on Monday but found no evidence of his whereabouts, as per local security and media reports.
Interior Minister Martin Niteretse stated at a press conference on Wednesday that the search for Bunyoni is ongoing, but he did not disclose the motives behind the operation.
A senior Burundian military official, who spoke to the AFP news agency on condition of anonymity, revealed that the former prime minister had been warned of the impending manhunt and "disappeared into the wild" before the arrival of the police.
The authorities have arrested a senior police officer for allegedly tipping off Bunyoni about the search operations.
Niteretse confirmed the arrest of a police colonel but did not provide further details.
Bunyoni, a prominent figure in the ruling CNDD-FDD party, was appointed prime minister in 2020 and dismissed shortly after President Ndayishimiye warned of a "coup plot" against him.
Bunyoni was considered the leader of the "hardliners" among Burundi’s generals, who hold substantial political power in the country.