The ongoing power blackouts will lead to job loses, the National Union of Metalworkers of South Africa (Numsa) said on Friday.

"One of the negative consequences of this load shedding, especially for the workers, is that industries heavily reliant on electricity for production are already contemplating cutting down the cost of production through retrenchments and lay-offs," Numsa KwaZulu-Natal regional secretary Mbuso Ngubane said.

"This will be a direct assault on the workers, amid the triple crisis of poverty, unemployment and inequality faced by the working class and the poor," he said.

"We call on government to take responsibility for the crisis, since their misguided decisions are haunting us now, and fix the crisis at Eskom."

He said the union was perturbed by the recent Eskom crises.

"It is now obvious to all that the parastatal's reliance upon coal is not only contributing to climate change more than any other institution in Africa, but it is a far less secure energy source than is claimed."

He said the continued blackouts had also reaffirmed the union's consistent calls for the strategic nationalisation of coal so that Eskom could supply cheaper electricity.