Opec member states lined up on Sunday to endorse a steep production cut agreed this month after the White House, stepping up a war of words with Riyadh, claimed Saudi Arabia had pushed some other nations into the move.

Iraq, Opec's second largest exporter, said the decision was based on economic indicators and was taken unanimously.

"There is complete consensus among Opec+ countries that the best approach in dealing with the oil market conditions during the current period of uncertainty and lack of clarity is a pre-emptive approach that supports market stability and provides the future the guidance it needs," Iraq's state oil marketer SOMO said in a statement.

Oman and Bahrain also said in separate statements that Opec+ – which includes other major producers, notably Russia – had been unanimous in deciding on the 2 million barrels per day reduction.

Algeria's energy minister called the October 5 decision "historic" and he and Opec Secretary General Haitham Al Ghais, currently visiting Algeria, expressed their full confidence in it, Algeria's Ennahar TV reported.

The cut came despite oil markets being tight, with inventories in major economies at lower levels than when Opec has cut output in the past.

But some analysts have said recent volatility in crude markets could be remedied by a cut that would help attract investors to a market that was underperforming fundamentals.

US National Security Council spokesman John Kirby said on Thursday that "more than one" Opec member felt coerced by Saudi Arabia into the vote, adding that the cut would also increase Russia's revenues and blunt the effectiveness of sanctions imposed over its invasion of Ukraine.

Oman's energy ministry said Opec+ decisions were based purely on the realities of market supply and demand. (Reuters)