The ANC yesterday shot down Eskom's application for a 53percent tariff hike, saying the electricity utility did not deserve the increase.
The ruling party also said the move would harm the poor.
"We find it unfair that while Eskom has not demonstrated any ability to deal adequately with the current power crisis, it is eager to call for tariff hikes that would hit consumers hard in the pocket," the ANC said.
On Tuesday the National Energy Regulator of South Africa (Nersa) confirmed that the electricity utility had applied for a 53percent hike.
Nersa said it would give the application urgent attention "in view of the current electricity supply shortage and load shedding".
Eskom has come under fire for the outages that have afflicted everyone in the country and is threatening economic growth.
The electricity utility said the government had failed to provide funding for more power stations.
Rapid economic growth has forced the pace of demand and the current power stations are being forced to run much harder to supply the required energy.
The Reserve Bank's latest quarterly bulletin warned that higher electricity prices would lead to inflation.
The bank has called on Public Enterprises Minister Alec Erwin to resolve the problem with Eskom as soon as possible.