COSATU has threatened to call a national strike to oppose the tariff increases granted to Eskom by the country's power regulator, Nersa, yesterday.
The labour federation said it would explore all avenues to ensure electricity prices are not increased and would resort to a strike if all else failed.
"If no progress is made in these discussions the federation will not shrink from mobilising its members, and the wider South African public, in strike action and protests," spokesperson Patrick Craven said.
Cosatu, political parties and other organisations condemned the hike, arguing that the country's poor and businesses would be negatively affected.
The DA said Eskom's new tariff hike would result in consumers paying for the failures of the ANC and would raise funds for the ruling party through its part-ownership of Hitachi Power Africa.
"The announcement of yet another hike demonstrates that the ANC administration has once again fallen prey to precisely the same misguided logic that has dominated the ANC's approach to parastatals over the last decade," DA spokesperson Manie van Dyk said.
"Not for the first time, consumers are being made to pay for the failures of the ANC government."
The ANC's front company, Chancellor House, has a 25percent stake in Hitachi Africa, which has a multi-billion rand contract to fit new power stations with boilers. Much of the price hike will go towards the construction of new power stations.
PAC president Letlapa Mphahlele said the price hike was "another rip-off of the poor by the powerful".
"The fact that the ruling party stands to gain from the electricity price hike casts doubt on the integrity of Eskom," Mphahlele said.
The ID also condemned the connection between the increase and Chancellor House.
"This means that the ANC will be making money off poor and ordinary South Africans. It is simply shocking that the government did not simply cancel the construction of Kusile, the second coal-fired power station proposed by Eskom," said ID chief whip Lance Greyling.
The SACP described the price hike as "a catastrophic betrayal of the poor who are bearing the brunt of the pursuance of a neo-liberal economic regime that did not encourage increased state investment where it mattered the most".
"That the majority of our people are expected to pay for the blunders of the elite is indeed very sad," said SACP spokesperson Malesela Maleka.
UDM leader Bantu Holomisa said he was disappointed.
"It is a sad day for our democracy when the public is forced to pay this unjustifiable secondary tax so that Eskom can finance its Hitachi deal, which the ANC will make billions of rands from at our expense," Holomisa said.
The ANC welcomed Nersa's decision to fix electricity tariff hikes at 25percent annually for the next three years rather than 35percent as requested by Eskom.
The ANC called on municipalities to respect Nersa's guidelines on increases.