* Bids due in Oct -OGX official
* Winning bid likely finalised by year-end
* Apart from Chinese firms, another 5 firms interested
* China's Sinopec, CNOOC independently studying data
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BEIJING, Sept 15 (Reuters) - Brazilian oil and gas start-up OGX SA will start taking bid proposals for its potential $7 billion asset sale in October, and may finalise the winner by year-end, an OGX official told Reuters on Wednesday.
The official also said that in addition to Chinese state company Sinopec Group and CNOOC Ltd, interested parties included one U.S. company, one Australian firm, two European companies and an Asian company.
The official, however, declined to comment about whether Sinopec and CNOOC would launch a joint bid but said the two companies were independently studying the data.
"We like the Chinese, because we understand there are many synergies, but it depends on what kind of deal is to be done," said the official on the sidelines of a China-Latin America investment forum.
"If the proposal is good for both sides we will finalise the winner by the end of this year. If not, we can reopen next year...We are looking for strategic partners."
OGX, part of the EBX industrial conglomerate owned by Brazilian billionaire Eike Batista, is considering sales of stakes in some of its oil blocks. The firm has made a massive natural gas discovery in its onshore blocks in recent months.
Sources have told Reuters that Morgan Stanley was advising Sinopec and Bank of America-Merrill Lynch was advising CNOOC.
(Reporting by Jim Bai and Chen Aizhu; Editing by Ken Wills)