Abu Dhabi National Oil Co. (ADNOC) said on May 12 it has reshuffled its leadership, in the first major shakeup since the appointment of Sultan Ahmed al Jaber as its CEO in February.

The reshuffle at the Gulf OPEC member's state-owned company comes as it seeks to award stakes in its 40-year onshore concession to develop the emirate's biggest oil fields after a deal with Western oil companies dating back to the 1970s expired in January 2014.

ADNOC named Abdulaziz Abdulla Alhari as director of its refining and petrochemicals division and Omar Suwaina al Suwaidi as director of its gas division, it said in a statement.

The firm also appointed new CEOs for six of its 18 operating units, including Adco and Adma-Opco, the joint ventures responsible for most of the emirate's oil production.

The appointments are all promotions from within ADNOC's ranks, following the retirement of two executives.