Public hearings hearings on Eskom's tariff application must be extended, the Democratic Alliance (DA) said on Monday.

The National Energy Regulator of South Africa's (Nersa's) hearings were not procedurally sound as the public had not been granted sufficient notice for comment on the amended application, the DA's shadow minister of energy Sejamothopo Motau said in a statement.

"The fact that Eskom changed its proposal means that it is in fact a new proposal with new issues on which the public needs to be allowed to comment and not allowing enough time for this is a misstep that must be addressed."

The tariff hike request was a direct consequence of the "chronic failure" of a State-owned enterprise to provide South Africans with an efficient, reliable and cost-effective service.

"The DA will be in contact with the Minister of Energy Dipuo Peters, to insist on an extension of the period for public comment as to ensure that the process is transparent and democratic."

Nersa's public hearings on the electricity utility's proposed 35% tariff hike for April 1, 2010 to March 31, 2013 began earlier on Monday in Mpumalanga.

Eskom, Sappi SA, TSB Sugar, Mpumalanga Cane Growers, the South African Institute of Electrical Engineers, the Congress of South African Trade Unions and Tankless Geysers for Africa participated.

On Tuesday, the public hearings move to Limpopo. They will be held in all provinces and end on January 21 in Gauteng.

The electricity parastatal has argued that it had to raise its tariff in order to fund its R385-billion expansion plan.