Opec clinched a deal to curtail oil supply, confounding sceptics as the need to clear a record global crude glut — and prove the group’s credibility — brought its first cuts in eight years.

An informal Opec meeting next month is unlikely to deliver any agreement to limit production because several members including Iran are still pumping below capacity.

Oil producers outside of the Organisation of Petroleum Exporting Countries (Opec) should cut “irresponsible” output with excess supplies harming the market, said the United Arab Emirates energy minister.