Abu Dhabi has asked international oil companies vying for a stake in its onshore oil fields concession to extend their bids by two months until 31 December, according to a report by Reuters citing sources familiar with the matter.

State-owned Abu Dhabi National Oil Company (Adnoc) is assessing bids from nine Asian and Western groups to form a new joint venture to replace the 35-year Abu Dhabi Company for Onshore Oil Operations (Adco) concession that expired in January.

Sources in the report claim that there is a difference of opinion in Abu Dhabi’s highest decision-making body – the Supreme Petroleum Council – over whether to stick with Western companies or make room for newcomers from Asia.

Abu Dhabi, the UAE’s largest emirate and one of the world’s biggest oil exporters, generates more than half its crude output from onshore fields.