Nigeria said on Sunday that two of its nationals were killed last month in South Africa following violent anti-immigrant protests targeting African workers in the country.

The Nigerians were killed June 28, two days before an unofficial deadline by protesters for foreigners to leave, the Nigerian Ministry of Foreign Affairs said. One was allegedly killed by police officers and the other by unidentified attackers, it said. South African police did not immediately respond to a request for comment from The Associated Press.

Anti-immigrant protesters in April and May blamed foreigners for high levels of unemployment, crime and pressure on public services. The violence at the protests and attacks on Africans prompted Nigeria, Ghana and Malawi to repatriate their citizens and summon South African diplomats.