The president of Bosnia’s autonomous Muslim-Croat federation, Zivko Budimir, has been arrested with 19 others in the most high-profile anti-corruption operation since independence in 1992.
Local media had previously reported that he had accepted bribes in exchange for granting amnesty to a number of convicts.
Police sources said 10 government officials were arrested in the offices of the regional government but the remainder were suspected drug traffickers.
They said one of the traffickers had previously been pardoned by Budimir.
Federation Vice President Mirsad Kebo says he had earlier asked the Constitutional Court to begin an investigation into the legality of certain amnesties over the past two years.
Budimir is at the centre of a political crisis that began in the federation last year.
He is refusing to approve a regional government reshuffle and is delaying the appointment of judges to the Constitutional Court.