Johannesburg's licensing and testing stations were closed on Thursday and only a few traffic officers were on the streets in a protest by union members at the metro police department.

The department was left with a small number of workers due to SA Municipal Workers Union (Samwu) members being unhappy with the return of metro police chief Chris Ngcobo, spokesperson Inspector Edna Mamonyane said.

"Service has been affected in our licensing and testing stations, the call centre, the accidents office and there's a shortage of traffic personnel due to the interruption."

The few metro police officers that came to work were sent to serious accidents, hence their low visibility throughout the city.

"I don't know what to call this, because we have not received any notice for a strike. Yesterday [Wednesday] workers obtained permission to have a meeting between 10am and 12 noon, but they did not return to work afterwards."

Samwu chairperson Ishmael Mangole said he was not aware of a strike.

"All I know is that members are waiting to be addressed by the city manager [Mavela Dlamini] or a representative from his office. We wrote the city manager a letter voicing our dissatisfaction with the outcome of the investigation [into Ngcobo's conduct].

Ngcobo was recently cleared of misconduct charges and re-instated following a probe by the City of Johannesburg. This raised Samwu's ire and it went on strike last year, calling for his dismissal.

The metro police boss was accused of failing to perform his duties, failing to act decisively on allegations about three suspended employees and promoting corruption by giving some employees allowances.

Ngcobo stepped down and the investigation followed. "What we are saying is that we distance ourselves from the outcome of the investigation," Mangole said.

Ngcobo returned to work on Monday.