ABU DHABI  - Abu Dhabi National Oil Company (ADNOC) said on Tuesday it was launching a competitive exploration and production tender for six oil and gas blocs, its first ever.

Two of the six blocks are offshore and four are onshore and estimates suggest they contain "substantial amounts of oil and gas", ADNOC said in a statement.

Successful bidders will have the opportunity to explore and then develop and produce blocs with ADNOC.

Bids are due by October and the first bidding round is expected to conclude this year.

(Reporting by Rania El Gamal; writing by Maha El Dahan; editing by Jason Neely) ((Maha.Dahan@thomsonreuters.com; + 9712 4082101; Reuters Messaging: maha.dahan.thomsonreuters.com@reuters.net))