A Nigerian group called for the International Criminal Court (ICC) on Thursday to investigate Zulu King Goodwill Zwelithini for "hate speech" blamed for a wave of violence against immigrants in South Africa.
South Africa this week deployed soldiers to try to quell anti-immigrant unrest that has killed at least seven foreigners, after being criticized by China, Zimbabwe and Nigeria for failing to protect their citizens against armed mobs.
Zwelithini was accused of sparking the trouble with comments in which he urged South Africans to "pop our head lice."
"We must remove ticks and place them outside in the sun. We ask foreign nationals to pack their belongings and be sent back," he told supporters at a stadium in Durban a month ago.
Nigeria's Socio-Economic Rights and Accountability Project in a statement called on the ICC to "investigate allegations of hate speech by the Zulu King Goodwill Zwelithini, which has resulted in killing, violence and discrimination against Nigerians and other African citizens."
Zwelithini has since defended his speech as having been taken out of context, saying attacks on immigrants are "vile."
Nigerians are furious, and the foreign ministry summoned South Africa's high commissioner this week.
"Nigeria ... spent a lot of money to fund the anti-apartheid struggle, ensuring that many South African students enjoyed scholarships in Nigerian universities," The Punch newspaper wrote in an editorial on Thursday.
"Yet, the relationship between South Africa and Nigeria since the end of apartheid ... has been that of contempt by the former towards the latter."
Isolated counter-protests involving a few dozen people have occurred in Nigeria, including one outside the South African embassy in Nigeria on Wednesday. South African firms such as mobile phone giant MTN and supermarket chain Shoprite have significant interests in Africa's biggest economy.