Opec agreed yesterday to curb its output by 1.2 million barrels per day, its first cut for more than two years, to halt a precipitous fall in prices.
The reduction, amounting to 4.3 per cent of Opec's September production, was deeper than anticipated and the biggest since January 2002. It trims Opec output to 26.3 million bpd from November 1.
"The credibility of Opec is at stake," Algerian Energy and Mines Minister Chakib Khelil said before the meeting that began on Thursday and ended in the early hours yesterday.
Some ministers said a further cut of 500,000 bpd could follow when Opec next meets in Abuja in December, to address high fuel stocks in consumer countries, particularly the US, and a projected drop in demand for Opec oil in 2007.
US oil rose 73c to $59.23 on the news, but later pared gains and was trading 44c higher at $58.94 a barrel by 0829 GMT.
In a statement issued after the meeting, Opec expressed concern that oil supplies were far outstripping demand.
"The over-supply situation and imbalance in supply/demand fundamentals have destabilised the market," it said.
Mr Khelil said all 10 Opec members subject to quotas would participate in the cut. Only Iraq, struggling to get its oil industry back on its feet after war and sanctions, was exempt.
"Everybody has a share," Mr Khelil told reporters.
Ministers were aware their failure to speak with one voice in the two weeks leading up to the hastily-arranged talks had contributed to oil's slide to $58 a barrel this week, 26 per cent off its mid-July peak and near its lowest level this year.
Once in Doha the group that pumps over a third of the world's oil presented a united front.
Saudi Oil Minister Ali Al-Naimi broke his public silence to say the world's leading exporter fully supported the plan to cut supplies and he flagged further cuts may lie ahead.
"This is not the end of the road," he said.
Gary Ross, CEO at PIRA Energy consultancy, said it was clear Opec meant business.
"Opec sees itself being challenged by financial speculators and will respond aggressively to make clear to the market its price objectives and willingness to cut volumes to achieve these objectives," Mr Ross said.
Arriving in Doha, ministers already had a pretty clear idea of their individual production cuts. There was broad acceptance that reductions must be made to real oil supplies rather than nominal quotas that have little relation to the barrels pumped.
But members jealously guard their quotas that are bound up with national price and market share.
In the days before the meeting Iran and Venezuela, struggling to meet their official limits, were wary of a supply-based cut that would see them ceding market share to Opec producers that were pumping far above quota, notably Algeria.
Opec found a middle ground yesterday.
To sidestep the issue of quotas and market share, it published only a list of individual cutbacks without giving the basis for the calculation or new national limits.
Opec's biggest member, Saudi Arabia, will shoulder around 32 per cent of the cut, amounting to 380,000 bpd.
Iran, Kuwait and Venezuela will cut at least 100,000 bpd.
Analysts said Opec's next task was to prove to the market it really was curbing supplies. Saudi Arabia said it had already notified its customers of cuts to November exports.
"The group must provide the market with a credible scheme or prices may fall further," ABN AMRO analyst Geoff Pyne said.
Algeria's Khelil said a $50-$60 price range for Opec's basket of crudes, last valued at $55.27 a barrel, would be acceptable to oil producers and consumers. That would put US crude between $55-$65 - three times its price in January 2002.