PRAGUE, Sept 3 (Reuters) - The Czech anti-monopoly

office UOHS said on Tuesday it had started official proceedings

on appeals from Westinghouse and EDF against the choice of South

Korea's Korea Hydro & Nuclear Power Company (KHNP) as preferred

bidder to build two nuclear reactors in the Czech Republic.

Legal disputes are a potential sticking point in the tender

for building two 1,000 megawatt units in the largest-ever Czech

procurement deal, expected to be worth about $18 billion at

current prices.

The Czechs plan to use the new units, together with small

modular reactors and renewable sources, to replace a fleet of

coal-fired plants as well as some older nuclear reactors that

are nearing the end of their lifespan.

UOHS said in a statement it could not estimate how long the

appeals process would run due to the complexity of the issue.

UOHS said the EDF complaint demanded that UOHS cancels

decisions by a unit of the majority state-owned CEZ on

evaluating bids.

The Westinghouse complaint focused on usage of a national

security exception that suspended public procurement rules, it

said. It also appealed a decision not to be invited into the

second round of the tender.

CEZ had earlier said that it believed that the security

exception made it impossible to challenge the process at the

anti-monopoly office. It had no immediate comment on Tuesday.

Westinghouse was not invited for the final round of bidding,

in which KHNP beat EDF, after it failed to put in a binding bid.

The government and CEZ hope to conclude negotiations with

KHNP and sign contracts by next March, and complete the first

reactor by 2036.

Westinghouse said in a statement last week it had appealed

also on the grounds that KHNP did not have a licensing agreement

to export its reactors, which are based on Westinghouse

technology.