Abuja: Nigeria yesterday said it had summoned South Africa's top diplomat to register its fears about a fresh wave of violence against immigrants near Johannesburg and Pretoria. Junior foreign minister Bukar Ibrahim said the high commissioner would be "informed of (the) government's concerns on the situation" and asked to ensure action was taken. "The Federal Government of Nigeria strongly urges the South African Government to take all necessary measures to protect the lives and property of foreigners living and working in South Africa," he added in a statement.