The Dukovany nuclear plant in the southern Czech Republic has increased its total power output to 2,000 megawatts following an extensive upgrade, a plant spokesman said on Tuesday.

Spokesman Petr Spilka from state-run power group CEZ said that one of the plant's four units was now running at 98 percent of capacity pending final tests, but that the other three units are working at full potential.

The increase has brought Dukovany's output in line with the Czech Republic's other CEZ-owned plant in Temelin, also in the south of the country.

Temelin's nuclear-powered output is expected to grow after the construction of two new units worth an estimated 20 billion euros ($25 billion).

The bidders for the upgrade project -- groups led by US giant Westinghouse, Russia's Atomstroiexport and France's Areva -- are due to submit final bids on July 2, with the winner to be announced next year.

CEZ, a major European energy producer, relies on the two plants for about 30 percent of its total power output, but the share is expected to rise to 50 percent after the completion of Temelin.