TOKYO, July 28 (Reuters) - Abu Dhabi National Oil Co (ADNOC) expects to make a final decision on whether to renew Japanese firms' oil concessions in Abu Dhabi oilfields before year-end or very early next year, its top executive told the Nikkei business daily.

The majority of Japanese stakes in Abu Dhabi oilfields including Inpex Corp's 12 percent hold in the massive offshore ADMA block are set to expire in March 2018, and high-ranking Japanese government officials have been frequently visiting the OPEC nation to win extensions.

ADNOC is making "good progress" in the talks on the stakes and any agreements would be new contracts with "new terms and conditions" rather than extension of existing contracts, group chief executive Sultan Al Jaber told the Nikkei.

Al Jaber indicated the possibility of roping in new partners from other countries such as China and South Korea in addition to existing stakeholders such as oil majors BP and Total , it added.

ADNOC has a long-term contract to sell liquefied natural gas (LNG) to the world's top LNG buyer JERA Co, a fuel joint venture between Tokyo Electric and Chubu Electric , which expires in 2019.

Al Jaber said ADNOC would "do everything possible" to continue LNG sales to Japan, the Nikkei said.

An ADNOC official confirmed that the interview with Nikkei took place last week.

(Reporting by Osamu Tsukimori; Editing by Joseph Radford and Clarence Fernandez) ((osamu.tsukimori@thomsonreuters.com, +813 6441 1857, Reuters Messaging: osamu.tsukimori.thomsonreuters.com@reuters.net;))