Four Nigerian police officers, accused of setting up an illegal checkpoint to extort drivers, messed with the wrong man: the head of one of the country’s anti-corruption agencies.

Musa Aliyu, who heads the Independent Commission on Corrupt Practices and Other Related Offences, has alleged that he was stopped while driving in the capital Abuja on Saturday and forced to withdraw 53,000 naira (£28; $38) from an ATM.

Police Commissioner Ahmed Sanusi accused the men of abandoning their official posts to set up the unauthorized roadblock.

They now face police disciplinary proceedings that could lead to their dismissal. It is rare for these types of cases to end up in court.

Aliyu’s report of the incident to the police sparked what the commissioner described as an “intelligence-driven operation”. This led to the arrest of the alleged ringleader and later the other suspects.

In an interview with BBC Hausa, Aliyu explained what happened after he was stopped on a busy road.

“When I stopped, a police officer came to my car door. I rolled down the window and he told me to open the car, so I did.”

Then the policeman came in.

“Then he asked me for my driver’s license. I took it out and he asked me to give it to him, so I did. Then he said he was going to take me to court for violating traffic rules. I said, ‘Let’s go to court.'”

But instead, Aliyu alleged, the policeman asked him for money, telling him: “You are a big man; you wouldn’t want us to waste our time, but even if we go to court, you will be fined N52,000.”

“I asked him to give me his bank account number so I could transfer the money, but he refused.” Instead, Aliyu alleged, he went to an ATM and withdrew the money.

The national police chief strongly condemned the officers’ alleged conduct and warned that the command would not tolerate further abuses of power.

“You have to choose: cop or thief,” Sanusi said. “You can’t be both. If you don’t choose, your actions will determine where you belong.”

Badariyya Kalarawi additional information