This decision was taken by the inter-ministerial committee on xenophobia in a meeting earlier on Friday.
The committee is headed by Minister of Police Nathi Mthethwa, who was also present at the briefing along with Minister of State Security Siyabonga Cwele, Cape Town Mayor Dan Plato and other government officials.
Zille said the UNHCR had an international mandate and budget to deal with problems faced by migrants.
“This is an international problem,” Zille said. “Why are people forced to be refugees in the first place?”
Zille said the body was in a better position to deal with the root causes that led people to seek refuge in foreign countries.
The premier said R170m had been “taken away from other service delivery projects” to deal with the xenophobic violence of 2008.
“They just haven’t applied themselves to how they deal with it,” she said of the UN agency.
Zimbabweans living in South Africa, estimated to number about three million, are the biggest group of asylum seekers in South Africa.
However, most of those that have gone through the Department of Home Affairs have been declared economic refugees, not political refugees, since that country’s economy went into a downward spiral following political instability that intensified in the early 2000s.
Zille said their status did not preclude their plight from the mandate of the UNHCR.
Apart from calling in help, Mthethwa said the all levels of government had been engaging and that proposals on legislative changes had been made.
These included, he said, addressing gaps in immigration law, by-laws that govern the regulation of businesses, access to banking and land issues.
He maintained that criminality played a significant role in attacks in foreigners.
“This for us, by and large, has manifested itself as crime opportunistically used” by people within communities.
Zille said plans to prevent wide-scale xenophobic violence in the Western Cape, where most attacks had been reported in the past week, were working.
She said the province had identified flash points, deployed mediators, was working closely with the police to ensure early responses and building partnerships with NGOs and churches.
“What could have been mass displacement is minimal displacement,” she said, adding that the challenge now was to build a culture of tolerance among communities for foreign nationals. News 24