The officers allegedly arrested a man after leaving a bank and took him to the station where they labelled him a 'Yahoo boy' - they extorted N50,000 from him.
The affected policemen, namely Mufutau Olaosun, Adebayo Temitope, Bakare Taiwo and Adesoye Ayokunlehin, were attached to Ijebu-Ode area command in Ogun state.
They were said to have extorted N50,000 from a man they arrested on trumped up charge.
The officers were fired after they were found guilty in an orderly room trial at the area command headquarters, Ijebu-Ode, Abayomi Sogunle, assistant commissioner of police, said in a statement.
He said they were with discreditable conduct and corrupt practice under the first schedule of police act and regulations Cap. P19. laws of the Federation of Nigeria 2004.
The statement read, "The four men on June 7, without any grounds, arrested a man who was just leaving a bank and took him to the Igbeba station, where they labelled him a ‘Yahoo boy’ and made him to frog jump and write a self-incriminating statement, that he was an internet fraudster.
"After the maltreatment, they released the man and also impounded the N50,000 he had gone to collect on behalf of his boss, saying it was payment for his bail.
"The man lodged a complaint with the police public complaints rapid response unit.
"The police authorities found the complaint genuine and were mortified that policemen could take money for bail, despite the #BailisFree campaign by the police themselves.
"Their action is contrary to the directives of the Inspector-General of Police and unacceptable."
Shogunle said the money has since been recovered from the four policemen and given back to the complainant.