PRAGUE CEZ submitted an application to the Czech State Office for Nuclear Safety on Friday to build two new blocks at its Temelin nuclear power plant.
The filing is the next step in the multi-billion dollar tender to expand the 2,000 MW power plant in the country's largest ever energy deal.
Lobbying is building in the closely contested tender in which Toshiba's U.S. unit Westinghouse and Russia's Atomstroyexport, in a consortium with a Russian-owned Czech group, are bidding.
U.S. Secretary of State Hillary Clinton will meet with Foreign Minister Karel Schwarzenberg in Prague on Monday. The U.S. State Department said on its website that Clinton would "meet with Czech officials on strengthening Czech energy independence."
She will likely visit Prime Minister Petr Necas and media have reported the Temelin tender will be high on the agenda.
The majority state-owned CEZ wants to sign a contract by the end of 2013. Media and analysts estimate it will be worth more than $10 billion, although CEZ has never stated a price tag.
CEZ, central Europe's biggest energy group with a market capitalization of $18.2 billion, threw out French Areva's bid in October because it failed to meet "crucial requirements".
The French have appealed to the Czech anti-monopoly office, which has said CEZ cannot sign a contract for Temelin's expansion until it rules.
Clinton's meeting in Prague follows the visit of U.S. Assistant Secretary of Commerce Nicole Lamb-Hale this week.
"We hope that the tender will successfully take place and we hope Westinghouse will be picked," she told newspaper Hospodarske Noviny in an interview published on Friday.
She said the U.S. Export-Import Bank was interested in financing the deal and would meet with the Czech government's special envoy for the Temelin tender Vaclav Bartuska in Washington on Friday.
The Czech nuclear energy push has run into opposition from neighbors Austria and Germany, but is the cornerstone of a government drive to secure its energy future.
Many top Czech officials fear an over-reliance on Russian energy will put the central European state under too much influence from its former communist master.
The Russian bidders have tried to allay worries and have lobbied mainly at industry level, where they historically have strong ties with Czech companies, and have stressed a high participation of domestic firms if they won the tender.
(Reporting by Jason Hovet and Jan Korselt; Editing by Elaine Hardcastle)