Allegations that "shoot to kill" orders had led to an increase in the number of shootings involving police must stop, the South African Policing Union (Sapu) said on Wednesday.

Sapu called on community members and the media "to stop making untested allegations that the alleged increase in the number of shootings involving members of the South African Police Service (SAPS) and alleged suspects or mistaken identified suspects is a result of what is commonly known as shoot to kill order by the police minister".

National police chief Bheki Cele is on record as saying police should not die with their guns in their pockets, but instead "shoot to kill at criminals".

"We must not be judged as being defensive, however we find it totally unacceptable and irresponsible when people undermine due processes and just pronounce without any facts," Sapu's general secretary Oscar Skommere said in a statement.

He said the Independent Complaints Directorate (ICD) was the only legitimate forum to investigate police brutality and deaths as a result of police action.

The ICD is investigating three incidents in which police officers allegedly shot dead four people over the weekend.

On Saturday, Kgothatso Ndobe, 21, was shot dead allegedly by a police officer, at his home in Atteridgeville, west of Pretoria.

The Sowetan newspaper reported on Monday that Ndobe's family and friends said he panicked when he saw the police because he was smoking dagga.

He allegedly ran and a police officer fired a shot that hit him in the head. Moments later, he was found dead inside a drain.

Two more killings were being investigated by the ICD, following a police raid that turned violent at Matsulu outside Nelspruit.

Mpumalanga police said the Matsulu community alleged that two people were shot dead by police during the weekend raid.

Two off-duty Pretoria policemen were arrested for allegedly shooting dead a street vendor after refusing to pay him in the early hours of Sunday.

The officers, stationed at Pretoria Central, were on their way from a pub to the police barracks when the incident happened.

"We send heartfelt condolences to the family of those people who might have been mistakenly killed by police officers whilst on duty," said Sapu.

It called upon its members to exercise extreme caution when taking huge decisions but at the same time, not allow themselves to be easy prey of ruthless criminals.