Migrants from various countries in Africa have criticised the police in Johannesburg for not doing enough to combat murders of foreigners by a local gang.

Many migrants say they are too afraid to speak out although they believe they know the identity of the killers.

They say at least six migrants have been killed in the past few months.

The BBC correspondent in Johannesburg says the South African government and human rights groups have expressed concern about a rise in xenophobia and racial violence by blacks against blacks.