* U.S. private equity firms also bidding - reports
* Deal could be worth as much as $9 bln - reports
* Nexon founder wants to sell stake in parent NXC Corp (Adds Blackstone's response in paragraph 9)
SEOUL, Feb 21 (Reuters) - South Korean tech firms Netmarble and Kakao and private equity fund MBK Partners have submitted initial bids to buy the parent of gaming firm Nexon, the Seoul Economic Daily said.
The newspaper and another daily said U.S. private equity firms were also bidding for NXC Corp, which controls Nexon.
Nexon founder Kim Jung-ju wants to sell a 98.64 percent stake in NXC Corp that is held by him and related parties including his wife. The deal could be worth as much as $9 billion, South Korean media reports have said.
Netmarble and Kakao, both backed by Chinese social media and gaming giant Tencent, have shown an interest in securing control of Nexon, South Korea's biggest gaming company.
NXC, Netmarble, Kakao, MBK Partners and Tencent declined to comment on the reports.
A source familiar with the matter told Reuters that MBK Partners planned to submit an initial bid for NXC, saying the deadline was midday New York time (1700 GMT) on Thursday.
U.S. private equity firms KKR & Co Inc and TPG Capital Management LP also submitted bids, Seoul Economic Daily said. Korea Economic Daily listed Blackstone and Bain Capital among the bidders.
People familiar with the matter told Reuters Blackstone had not submitted a bid.
Blackstone, Bain Capital, KKR and TPG Capital declined to comment.
Korea Economic Daily also said earlier in February that Netmarble, which controls more than a quarter of South Korea's mobile gaming market, would partner with Tencent and MBK Partners in a bid.
Reuters reported in January that Deutsche Bank and Morgan Stanley were running the sale.
Deutsche Bank declined to comment on the reports, while Morgan Stanley was not immediately available for comment. (Reporting by Hyunjoo Jin, Kane Wu and Heekyong Yang Editing by Muralikumar Anantharaman and Edmund Blair)