Energy Minister Dipuo Peters on Thursday said she has not yet considered questions raised over profits the African National Congress (ANC) stands to make from new power plants through its investment vehicle Chancellor House.

"The interest of ANC in privatised power... I haven't applied my mind to that particular issue, but I would believe that at a later stage I could respond," she said at a briefing about Eskom's new tariff hikes.

Opposition parties said this week that the ANC would profit handsomely from the new 25% annual increases in electricity prices meant to pay for two new Eskom plants in Limpopo and Mpumalanga.

Multi-billion rand contracts for boilers for the plants have been secured by Hitachi Power Africa in which Chancellor House holds a 25% stake.

The media has reported that R5,7-billion was a modest estimate of the amount the party could make from the construction of the new Medupi and Kusile plants.

The Independent Democrats on Wednesday charged that "most of the billions in increases ordinary South Africans will be forking out for electricity will be going to a foreign company Hitachi and its local partner, the ANC front company Chancellor House."

ANC treasurer-general Mathews Phosa two years ago gave assurances that the party would divest from the power plant deal in a transparent manner.

He declined to discuss the issue on Thursday, dismissing questions as "unethical".