UPDATE 1-Intel to challenge South Korea antitrust ruling

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SEOUL, Dec 10 (Reuters) - Intel Corp (INTC.O) said on Wednesday it had filed a formal complaint to overturn an earlier South Korean antitrust ruling that found the world's biggest semiconductor maker had abused its dominant market position.

Intel said in a statement its filing to the Seoul High Court asserted that the Korea Fair Trade Commission (KFTC) made substantial factual and legal errors in formulating its final opinion.

The KFTC said in June that Intel offered rebates to South Korean personal computer makers in return for their not buying microprocessors from rival Advanced Micro Devices (AMD.N). Intel was also fined about 26 billion won ($18 million).

"The KFTC failed to understand the dynamics, pricing and competition in the microprocessor market," Intel said in a statement, adding that the South Korean regulator either misinterpreted or ignored evidence of benefits to consumers from cheaper, improved Intel chips.

Intel denies "artificial price protection," but "competes aggressively," said Nick Jacobs, an Intel spokesman.

The KFTC declined to comment. It said in June Intel's rebates limited the choices of domestic PC makers in selecting business partners and forced local consumers to buy PCs at higher prices.

Intel is also facing competition charges from the European Commission and an antitrust investigation by the U.S. Federal Trade Commission. ($1=1430.0 Won) (Reporting by Rhee So-eui; Editing by Keiron Henderson and Jonathan Hopfner)