More than two million South African workers have been warned against participating in planned anti-immigrant protests set for June 30, as the country braces for potential unrest amid rising xenophobic tensions.

Four of South Africa’s largest labour federations, including the Congress of South African Trade Unions (COSATU), said workers who skip work to join demonstrations may not receive union protection.

Together, the federations represent over two million workers.

“We urge workers to report for duty and not place their employment at risk,” the unions said in a joint statement, according to Reuters.

The warning comes as anti-immigrant groups push for undocumented foreigners to leave the country by June 30, following weeks of protests and sporadic attacks targeting migrants.