South African police investigating the rape and murder of two toddlers whose bodies were found in a public toilet, have arrested a fifth man, described by local media as the prime suspect in the crime.

The mutilated bodies of the girls aged two and three were found in the north Johannesburg township of Diepsloot on
Tuesday, three days after they were reported missing.

We condemn these murders in the strongest possible terms

President Jacob Zuma

Four other suspects are already in custody and will appear in court in Pretoria on Friday.

"He was arrested in Alexandra in the early hours of this morning. He is part of the group suspected of the killings," Lungelo Dlamini, a police spokesman, said.

The arrest of the fifth suspect in another Johannesburg township came after police issued an identikit and offered a $10,200 reward.

He is likely to appear in court next week.

On Friday, the director of the Children's Institute at the University of Cape Town, Shanaaz Mathews, said three children were murdered everyday in the country.

Speaking to the South African Broadcasting Corporation, Matthews said children were especially vulnerable to abuse as they were considered "easy targets".

Earlier in the week, President Jacob Zuma expressed shock at the murders, describing the incident as "gruesome".

Zuma, speaking on Tuesday, urged residents of Diepsloet not to take matters into their own hands.

"We condemn these murders in the strongest possible terms," he said.

"Whilst we appeal to the communities not to take the matters into their hands, we also want to urge them to work with law enforcement authorities to find the perpetrators and prosecute them to the fullest extent of the law."

Residents of Diepsloot went on the rampage after the bodies were discovered, demanding better policing.

The killings have shocked South Africa, a nation plagued by some of the world's highest rates of violent and sexual crime.

Source: Agencies