A parliamentary task team investigation believes there "is a third force" involved in orchestrating xenophobic attacks.
The task team said yesterday that it had found evidence that specific groups were coordinating the attacks - but did not know who or what their agenda was.
The team has also visited Gauteng townships and informal settlements to investigate the reasons behind the attacks.
The leader of the task team, Obed Bapela, said: "Among the people arrested were some found in possession of weapons, some of them were being transported from one place to another. The question that remains unanswered is where do these people get weapons, money and the means of transportation?"
Bapela said the attacks had been well planned.
"The attacks started in Alexandra and flared up to Ekurhuleni and then to other places. That is exactly how they were planned," he said.
Bapela said while visiting the affected areas in Gauteng, a foreign national in Tembisa told them that he "did not know" the people who had attacked them.
"He said he had never met the people before."
Bapela said most of the people arrested were from hostels around the affected areas.
Residents at Zamimpilo informal settlement in Industria, Johannesburg, where more than 50 shacks were burnt, said their attackers had arrived in minibus taxis.
Last week government officials suggested that a "third force" was orchestrating the violence.
Bapela also called on the public to report the perpetrators of violence and also help rebuild the image of South Africa.
In response, Department of Safety and Security spokesman Hangwani Mulaudzi said: "It does not matter whether there was a third force involved or not. All that we want to do is to deal with the problem we are faced with and find solutions."