Iran has rejected an offer from Saudi Arabia to limit its oil output in exchange for its supply cut. This dashes market hopes that the two major OPEC producers will find a compromise this week to help ease a global glut of crude.

Despite that, Saudi Arabia's energy minister said the mood at the International Energy Forum was generally positive, as OPEC members met to discuss stabilising oil markets. An oversupply of oil has more than halved prices since 2014, prompting OPEC ministers and non-member Russia to seek a market rebalance.

But differences between Saudi Arabia and Iran remain. Both their economies depend heavily on oil, but Iran is seeing the pressure easing as it emerges from years of sanctions. Saudi Arabia, on the other hand, faces a second year of record budget deficits and is being forced to cut the salaries of government employees.