A South African police officer was charged with attempted murder on Friday after allegedly dragging a man alongside his car for about 100m.

The incident came two weeks after the death of a Mozambican taxi driver dragged behind a police van, piling pressure on police minister Nathi Mthethwa and renewing calls for a judicial commission of inquiry into brutality by the force.

The latest victim, a court interpreter, had intervened when he saw two officers allegedly harassing a boy near a tuckshop in Setlopo village in Mafikeng, North West province, according to the Independent Police Investigative Directorate (IPID).

"After the police had finished talking to the boy, the complainant called the boy to advise him about what to do should he feel that he was treated badly by the police," IPID spokesperson Moses Dlamini said.

The police officers then called the man over to confront him about what he had told the boy. "The driver grabbed the complainant by the neck and asked him if he knew what police were capable of these days," Dlamini continued. "The policeman allegedly drove off and dragged the complainant for about 100m."

The man suffered injuries to his feet and was taken to hospital by a neighbour. A 36-year-old sergeant was arrested and charged with attempted murder on Friday. The case was postponed until Wednesday for a formal bail application.

South Africa's police ministry condemned the incident. Spokesman Zweli Mnisi told SABC radio news: "This is an embarrassment ... it is disgusting."

The "issue of command and control" at police stations needed examination, he said. "What is the role of those who are supposed to claim oversight over this member?"

The opposition Democratic Alliance said it showed the need for "a concrete action plan to deal with systemic police brutality". Dianne Kohler Barnard, shadow police minister, said: "This latest incident, the latest in a string of embarrassing and unacceptable incidents which have fundamentally undermined the image of the South African police service, highlights the need for urgent action on police brutality by president Jacob Zuma and minister of police Nathi Mthethwa. Yet both have failed to show leadership on this issue."

Earlier this week nine police officers were denied bail after being charged with murdering taxi driver Mido Macia, 27, who was dragged behind a police vehicle in Daveyton, east of Johannesburg. Video footage of the incident caused an outcry in South Africa and around the world. Hours later Macia was found dead in the local police station's holding cells.

Mthethwa, a close Zuma ally who was away on honeymoon when the tragedy happened, spent about half an hour with Macia's family representatives on Thursday and walked the 500-metre route along which he was dragged.

"Police in this democratic dispensation are not allowed to brutalise people, but we hear stories of members of the SA police service doing that," Mthethwa said. "We do not want cop tsotsis [thugs]. We must ensure that we clean ourselves up, or lose the trust of the community."

On Friday the Sowetean newspaper highlighted yet another incident from July last year in which a female constable allegedly closed her car window on 20-year-old Kleinbooi Matthews and drove away with his head still inside, resulting in his death.

Meanwhile the beleaguered national police commissioner, Riah Phiyega, this week appeared at the commission of inquiry into the Marikana disaster, in which police gunned down 34 striking mineworkers. A statement released on behalf of the deceased workers' family rejected Phiyega's "condolences" and demanded "a full-throated apology".

About 932 people died in police custody in 2011-12, the IPID found. The seemingly constant barrage of negative revelations has left the force at one of its lowest points in public esteem since the dawn of multiracial democracy in 1994. "If this was apartheid police we'd riot," posted Zackie Achmat, a social activist, on Twitter. Commentators say there is no hope of salvaging their reputation without root and branch reform.

Gareth Newham, an analyst at the Institute for Security Studies, said: "It will keep happening because the fundamental reason is not being addressed. We've had poor leadership for at least a decade when Jackie Selebi [later jailed for corruption] was appointed.

"Police have not been accountable and it's just become the way they police. They use violence to command respect through fear from the community. It's a problem that won't go away until the police themselves accept responsibility."

Newham rejected the view expressed by ministers that only a small minority is culpable. "It's not a small number of officers responsible. It's systemic, it's widespread and it's going to keep on happening."

David Bruce, an independent researcher and expert on the criminal justice system, added: "They continue to see it as a 'bad apples' problem and don't understand what kind of culture it reflects and what interventions could address it.

"The minister has compounded the problem; during his period in office it has become worse as a result of his influence and encouragement of a more aggressive use of force in quite a crude way. In training, police are told they don't have to take the law too seriously."

Have you been affected by a similar incident in South Africa? Please email guy.grandjean@theguardian.com