PRETORIA (AFP) - South Africa's police minister on Friday argued that shotgun rounds are not live ammunition, as he answered questions about how five protesters died in separate clashes with police within two weeks.

Last week, four people were killed in a police crackdown on protests over poor water delivery in Mothutlung, a town west of Pretoria.

Three people died after officers said they fired into the crowd, while another was allegedly pushed from a moving police van.

"There was no live ammunition used," Police Minister Nathi Mthethwa said in Pretoria, the country's administrative capital.

"There are rounds that are known as SSG, or twelve-gauge rounds with pellets, so that's what was used, which was not supposed to be used," he said.

"But that's not live ammunition. As I say, it's mainly pellets." The Mothutlung officers acted against protocol and are being punished appropriately, said Mr Mthethwa.

"There is no carte blanche that we give to our officers to kill innocent people who protest," he said.

But, he added, "if somebody is trained to do something in a particular way and decides to do something else, I don't think that even the management can be blamed there." Fourteen officers were implicated in the Mothutlung protest and a case of four counts of murder and four of attempted murder has been registered.

Most of the officers at the Mothutlung protest were also working during the protests at Lonmin's Marikana mine in 2012, though Mr Mthethwa said the officers were pulled out before 34 striking miners were killed there in one day by police.

No officers have resigned over the Mothutlung deaths, said the police minister.

Six officers are under suspension, and the others are being served with suspension notices.

Meanwhile, police are also investigating the death on Thursday of a 28-year-old resident of Durban Deep, an informal settlement near Johannesburg, who died after police fired shots at protesters rallying against a possible forced eviction.

South Africa's police are frequently embroiled in allegations of brutality, but prosecutions are rare.

Experts count hundreds of violent protests over substandard delivery of housing, electricity and water every year in Africa's wealthiest country, which is dogged by stubborn levels of inequality.

"It's not just the fact that water isn't being provided, but there is a sense that local officials are corrupt and possibly inept," said Ms Karen Heese, an economist at Municipal IQ, a Johannesburg-based research organisation that monitors protests in the country.

"The worrying trend is just the level of police brutality, it's very unusual to have four deaths from a single protest," said Ms Heese.