A nuclear power deal between the South African government and Russia's state nuclear agency Rosatom has been declared “unconstitutional” by the country's High Court.
Judges ruled that the agreement was illegal because it had not been debated by the South African parliament, the country's Mail and Guardian newspaper reported.
Deals between the South African government and other nuclear agencies from South Korea and the United States were also nullified.
South African and Russian officials signed the intergovernmental agreement in 2014 to secure a co-operation between state-owned nuclear group Rosatom and state-owned utility Eskom.
The ruling casts doubt over South Africa's plans to boost the country's nuclear energy capacity by 9,600 megawatts (MW).
Numerous foreign agencies have expressed interest in the tender with South African energy agency Eskom, which could see up to 10 new reactors built in one of the largest nuclear power contracts in decades.
In a statement, Rosatom said that it still planned to bid on the Eskom tender.
"We cannot comment on the decision of the South African court regarding the actions of the former South African Energy Minister and Eskom. But we hope that South Africa will continue to view nuclear energy as a priority for the development of the country's energy sector," Viktor Polikarpov, Vice-President of Rosatom for Sub-Saharan Africa, told Russia's TASS news agency.
Companies from China, France, and South Korea are also set to bid on the contract.