Twelve people were arrested in connection with the violence in Alexandra township outside Johannesburg late on Sunday, which police said was motivated by a belief that illegal immigrants were responsible for a series of robberies.

"From what we were told it is because of the criminal activity that has been taking place," said Constable Neria Malefetse, a spokeswoman for the Johannesburg police.

The rampage rekindled fears that xenophobia was rising in a country known as one of the most welcoming to immigrants and asylum seekers, especially from Africa.

Some of those who were attacked were Zimbabweans, the largest immigrant group in South Africa who are often accused by residents of contributing to the country's high crime rate.

Last month, shacks belonging to Zimbabwean families in another township were looted and set on fire and there have been other attacks on foreigners throughout the country.

For decades Africans have flocked to South Africa, the continent's economic powerhouse, lured by abundant work in its mines, farms and homes and by one of the world's most liberal immigration and refugee policies.

Growing hostility towards this group threatens to damage South Africa's relations with other African countries and handicap its buoyant economy, under strain from rising inflation, a shortage of skills and a power crisis.

COLD SHOULDER

Many newcomers are being met with a cold shoulder and, in some cases, a clenched fist, according to relief workers and rights activists who have noted an rise in violence against foreign-born residents in the "Rainbow Nation".

"It's clearly something that has got worse this year. These are general attacks on foreigners," said Jack Redden, regional representative of the U.N. High Commissioner for Refugees in Pretoria.

"What has been really worrying is the violence that is attached to them."

It is unclear whether the rising cost of living and other economic jitters directly contribute to the violence. Fear of crime is generally given as the cause of attacks on foreigners, who are often blamed for murders, rapes and carjackings.

Immigrants say they are frequently the victims of crimes and their complaints are beginning to get attention.

Nigeria's Senate last month considered a motion condemning attacks on its citizens in South Africa. Zimbabwean rights activists accuse police of harassing immigrants and turning a blind eye when criminals prey on them.

An estimated three million Zimbabweans have fled to South Africa as a result of the economic crisis back home.

South Africa has acknowledged its concern about rising xenophobia within its borders and says it is taking steps to tackle the problem.