Correctional Services spokesman Manelisi Wolela has denied allegations that student leader Mcebo Dla.
Community leaders "incited violence against foreigners" to maintain their authority, a study commissioned by the International Organisation for Migration has revealed.
"The idea that the attacks were committed by a third force or faceless mobs does not hold. Street committees and community forums organised the attacks," said Jean-Pierre Misago of Wits University's Forced Migration Studies Programme.
The report, titled Towards Tolerance, Law and Dignity: Addressing Violence against Foreign Nationals in South Africa was launched in Johannesburg yesterday.
A campaign to counter racism, xenophobia and tribalism, called "One Movement", was also launched, with Archbishop Desmond Tutu as one of the patrons.
More than 60 people were killed and 670 injured in May last year during an outbreak of xenophobic violence.
The report found "political vacuums" in communities contributed to the emergence of "unofficial, illegitimate and often violent forms of local leadership" to drive out those considered outsiders.
Misago said the police did nothing to quell the attacks despite prior warnings.
He said baseless explanations such as crime, foreigners "stealing jobs and women" from locals, and poor border control were used to justify the violence.