The Hungarian official in charge of expanding the country's only nuclear power plant says the construction of two new reactors should start in 2018.

Attila Aszodi said Tuesday the new reactors are expected to begin supplying electricity in 2025 and 2026.

The expansion of the Soviet-built plant in the city of Paks will be completed by Russia's state-owned Rosatom and is being financed mostly with a Russian loan of 10 billion euros ($10.7 billion).

Aszodi said the five reactors in Paks currently provide 36 percent of Hungary's electricity supply but have to be shut down between 2032 and 2037. On their own, the new reactors would boost the plant's output by nearly 20 percent.

Critics say the project is too expensive and draws funding away from renewable energy sources.