PRAGUE (Reuters) - Czech majority state-owned utility CEZ has received updated binding bids from South Korea's KHNP and France's EDF in a tender to build up to four nuclear power units, the company said on Tuesday.

The Czech Republic, which plans to keep nuclear power as a major part of its energy mix in the coming decades, had widened the tender to possibly build multiple blocks with capacity of more than 1,000-megawatts each, up from an originally planned one unit.

The tender is structured as a firm bid for one unit at CEZ's Dukovany nuclear power plant, plus a binding option for up to three more: an additional unit at Dukovany and two at CEZ's Temelin facility.

The plan to expand nuclear power capacity got an added boost on Tuesday when the European Commission gave approval to state aid for building the first unit.

The government, which owns 70% in CEZ, said the decision could be a basis for support for any further blocks that the government decides to build.

The government will assess the suppliers' bids along with CEZ, one of central Europe's biggest companies with a market value of nearly $20 billion, and pick the winner in the coming months, seeking to sign a contract by end-March 2025.

"Nuclear now provides for more than a third of consumption in our country and it should be even half in the future," Prime Minister Petr Fiala said.

The government and CEZ widened the scope of the tender to help lower the price of each block in what is expected to be the country's largest energy investment to date.

CEZ has agreed a financing model with the government, including low-interest loans and guaranteed power sales prices, for the construction of one unit at Dukovany.

But management has said the company could not replicate the model four times, and critics have said the country, with gross domestic product of 293 billion euros ($314.13 billion), could find it difficult to finance four units.

Delays and cost overruns are common across the industry, but analysts have said that EDF's European production base and France's political support in the EU spoke to its favour.

The cost of EDF's 3,200-megawatt Hinkley Point C plant in Britain has more than doubled to $43 billion, plus a significant inflation adjustment, and its launch date has been pushed back by years.

KHNP has faced smaller delays to its 5,600-megawatt plant in the United Arab Emirates and has joined a project in Poland, but has yet to build a reactor in the EU.

The Czech government has yet to set the size of a loan that is part of the state support that received EU approval on Tuesday. It said guaranteed sale prices will be set for 40 years, longer than at Hinkley Point C, in a model to provide investor stability and the ability to repay the loan.

($1 = 0.9327 euros)

(Reporting by Jan Lopatka and Jason Hovet; Editing by Kirsten Donovan, Louise Heavens and Barbara Lewis)

By Jan Lopatka and Jason Hovet