A nuclear deal signed between Russia and South Africa on Monday will see Moscow offer technology and training to build a third nuclear reactor in the African state.

The agreement, which was signed in Vienna at an International Atomic Energy Agency conference is worth an estimated 40-50 billion USD given that one reactor costs around 5 billion USD, according to Russia's Itar-Tass news agency.

Russia's state-owned nuclear company Rosatom will build a large-scale nuclear power plant in South Africa and develop collaboration in its nuclear industry.

South Africa has previously signed nuclear co-operation agreements with other countries, including Russia.

Moscow is planning to build infrastructure in South Africa and train local nuclear specialists in Russian universities.

The new reactor is expected to come into operation in 2023. At present, South Africa has two nuclear reactors; one is for experimental research. The other generates 5 percent of the country's electricity needs.

South Africa's first commercial nuclear power reactor began operating in 1984.

The South African government's commitment to the future of nuclear energy is strong, with firm plans for further 9,600 MWe capacity in the next decade, but financial constraints are severe, say industry observers.