Earlier today, key members of the group had expressed confidence that a deal would be reached, Bloomberg reported on Sunday.

The start to the group’s meeting has been pushed back to allow for further talks, but a delegate said African quotas were still being negotiated.

Ministers held side meetings and shuttled between Vienna hotels late into the night on Saturday, and discussions continued Sunday morning as they sought to smooth over differences.

The United Arab Emirates was pushing for a change to the way its output cuts are measured, according to delegates. But the UAE’s gain would come at the expense of African countries asked to give up some of their unused quotas  —  a politically unpalatable option they were reluctant to accept.

The Organization of the Petroleum Exporting Countries and its allies are considering fresh production curbs just two months after unveiling a surprise cut.

Crude rallied briefly after that April announcement, but since then weak economic data from China and recession fears have weighed on oil prices, which fell 11% in May.

the 49th Meeting of the Joint Ministerial Monitoring Committee (JMMC) and the 35th OPEC and non-OPEC Ministerial Meeting

The meeting will be headed by Equatorial Guinea’s Minister of Mines and Hydrocarbons Antonio Oburo Ondo.

The inaugural ceremony of the 35th OPEC and Non-OPEC Ministerial Meeting (OPEC+) will be held on Sunday with the participation of heads of missions of the member states, OPEC secretary general and representatives of the media.

The Iranian delegation will be headed by Amir Hossein Zamaninia, Iran’s representative in OPEC Executive Board, and will take part in the meetings on behalf of Iranian Oil Minister Javad Owji.