Cape Town - United Democratic Movement president Bantu Holomisa has added his call for the ANC to rid itself of shares in companies that benefit from public contracts.
"It creates a conflict of interest that quite simply leads to bad governance and corruption," Holomisa said in a statement.
He was reacting to reports that the ANC was set to earn billions of rands through tenders given out by Eskom to Hitachi.
The ANC's investment arm Chancellor House owns 25%of Hitachi.
Eskom has proposed that electricity tariffs be increased by 35% a year for three years to fund its infrastructure expansion programme.
"We now have a situation where Eskom's plans are not possible unless they fleece the public with massive tariff increases," Holomisa said.
"And we have a ruling party that stands to benefit to the tune of billions of rands if Eskom continues with these plans. It is a preposterous situation."
"This type of behaviour could explain the lack of foreign direct investment."
"Whilst the ANC seems unconcerned, foreign investors view South Africa with trepidation because of the unspoken expectation that business partners and contractors have to be aligned to the ruling party."
Holomisa called for Parliament to appoint an independent judge to assist the National Energy Regulator of SA, which is currently holding hearings on the proposed increase.
Earlier on Thursday Democratic Alliance MP Sejamothopo Motau said there are "compelling reasons" to believe the ANC will benefit from Eskom's proposed electricity tariff hikes.
He said all indications were that the tender process where Hitachi won a R20bn tender to build a boiler for Eskom at Limpopo's Medupi power station was "flawed".
"The array of information available now in the public domain provides compelling reasons to believe that the ANC will benefit from higher Eskom tariff hikes," he said in a statement.
The ANC's treasurer Mathews Phosa had promised to take steps to disinvest the party's interest in Hitachi, which makes products ranging from home appliances to industrial machinery.
'No problem'
ANC secretary-general Gwede Mantashe said this week that there was nothing wrong with the party holding a stake in Hitachi.
Motau said several documents were now available publicly demonstrating the Hitachi tender was flawed.
"Last year, for instance, we released a confidential Eskom memo detailing how Hitachi's submission was relatively less applicable than the Alstom submission.
"Likewise, the Eskom letter leaked in 2008, entitled 'Summary of the Medupi Tender Process', demonstrates that the award of the R20 billion Medupi boiler contract should have been granted to the Alstom-Steinmüller consortium, and not to the Hitachi consortium."
Motau said Eskom had ensured Hitachi no longer had to compete with other suppliers for tenders.
"As a consequence, for every coal power plant that is now constructed, Hitachi's shareholders, including the ANC are ensured greater revenues."
He said the revelations "must call into question" Eskom's bid to raise electricity tariffs.
"We have already seen submissions by business and labour representatives that demonstrate how such a move would be disastrous for the South African economy.
"The only people who appear to stand to benefit are the ANC."
Lance Greyling, a member of the Independent Democrats, said earlier this week that much of Eskom's proposed 35% hike would be used to fund the construction of Medupi and the Kusile power station in Mpumalanga.
He said the largest component of the expenditure was for boilers for the two power stations, a contract worth R38bn in 2008.
Current estimates were that costs had risen from R78bn to R120bn and R85bn to R142bn for Medupi and Kusile respectively.
- Sapa