By Sylvia Westall and Barbara Lewis
VIENNA (Reuters) - OPEC ministers anxious to arrest a deep price slide and yet cushion a bruised economy said on Thursday they agreed they must cut output, but had not decided by how much.
International benchmark U.S. crude has slumped by more than 50 percent from a record high of $147.27 hit in July. On Thursday it was trading around $68 a barrel.
The plunge prompted the Organisation of the Petroleum Exporting Countries to bring forward to Friday an emergency meeting originally set for November 18 and it has revived memories of the 1998 price collapse when oil sank below $10.
On arrival in Vienna, Venezuelan Minister of Energy and Petroleum Rafael Ramirez said there was a risk oil could fall back to that level and OPEC needed to act without delay.
"We have to handle the situation in a very, very responsible manner as OPEC.... that way we can avoid a price collapse like 1998," he said.
"There's going to be consensus to take a very, very, very fast action," he said of Friday's meeting, adding his view was the group needed to agree an initial cut of at least a million barrels per day (bpd).
An OPEC source said OPEC's core Gulf producers would prefer a reduction of around one million bpd, but others in the group wanted a cut of closer to twice that.
Saudi Arabian Oil Minister Ali al-Naimi said merely that the oil price would be determined by the market. He would not be drawn on the need for any cut.
The only OPEC producer to be pumping significantly above its official output target, Saudi Arabia would be expected to lead any reduction in supplies.
As economic slowdown has destroyed demand for oil and stocks have built up, most OPEC ministers have said a cut was essential to limit oversupply, stave off a price collapse and protect their own economies.
But they also need to avoid inflicting more pain on their consumers or they could damage demand further still.
MORE THAN ONE CUT?
OPEC President Chakib Khelil of Algeria was among those who said cuts could be in stages and it could take more than one meeting to strike the right balance between supply and demand and between producer and consumer needs.
"The concern of the producing countries is, whatever decision is made, not to have an impact on increasing the pain of consuming countries," Khelil told a news briefing.
"The decision should not leave the producer countries in the situation where they will be joining the group of countries which are already suffering from the financial crisis."
Adding to the difficulty of its task, however deep a cut it agrees, OPEC could struggle to enforce it.
In the past, those members who most needed revenue were reluctant to limit exports when the market was weak. The producer group's lack of discipline was in part responsible for pushing oil to less than $10 during the Asian economic downturn.
Compared with then, even Venezuela and Iran -- which have big social spending plans and are said to have the highest price needs -- are better placed because they can live for a while off the profits of the record rally.
But any comfort they might take is offset by the scale of the global financial crisis. It threatens to destroy oil demand in emerging countries such as China, which had previously been expected to make up for any major drops in consumption in the world's biggest consumer the United States.
"I've seen a lot of crises. I saw the Asian crisis. I saw the Japanese crisis," said Qatari Energy Minister Abdullah al-Attiyah. "I've seen different crises here and there, but to see this kind of financial crisis, I have never seen it before."
(Additional reporting by Michael Georgy, Peg Mackey, Luke Pachymuthu and Rania El Gamal; writing by Barbara Lewis, editing by William Hardy)
(OPEC newsroom +431 712 0747)
