KHNP beat France's EDF in the tender launched in 2022 for one new reactor at the Soviet-built Dukovany power plant.

But Prague said later it was seeking bids for a total of four new units: two for each of its two nuclear plants in Dukovany and Temelin.

"The Korean bid was better in all criteria assessed," Fiala told reporters.

"We have decided to build two units at Dukovany for now," Fiala said, adding the government would discuss an option for another two units at Temelin.

Fiala said the price offered by KHNP beat expectations, reaching around 200 billion Czech koruna ($8.65 billion) per unit if two units are built.

He added that Czech companies would participate in about 60 percent of the construction.

The government said earlier it expected to sign a deal with the winner by next March, the construction to begin in 2029, and the first new reactor to be launched in 2036.

EDF has lobbied hard for the contracts and French President Emmanuel Macron visited Prague in March to push its bid.

CEZ currently runs six nuclear units at the two plants located in the south of the country.

Industry and Trade Minister Jozef Sikela told reporters on Wednesday the plants accounted for around 30 percent of the Czech electricity output.

"It will be roughly 50 percent in the future," Sikela said, calling nuclear energy "the pride of Czech energy production".

The government earlier eliminated US giant Westinghouse from the tender over flaws in its offer and Russia's Rosatom and China's CGN on security concerns.