The United States is leading consumer nations calls for OPEC to open the taps on any spare capacity to ease high world oil prices.
U.S. Energy Secretary Spencer Abraham said on Friday that OPEC members Saudi Arabia, Kuwait, the United Arab Emirates, and Nigeria had all indicated willingness to increase production along with non-OPEC Mexico. He also praised Russia for its plans to boost export capacity.
Here are some details of what those countries, and other sources, have said about their spare capacity.
Leading OPEC member Saudi Arabia has said it maintains 10.5 million barrels per day of total crude production capacity.
It says this production could be brought on in 72 hours, although new wells would need to be drilled to maintain production at this level.
Saudi Oil Minister Ali al-Naimi said in Amsterdam last weekend the Kingdom would raise June production to nine million bpd in June, compared to an IEA estimate of 8.3 million in April, and would go further if there was demand.
Riyadh may invest in new capacity above 10.5 million bpd if demand is maintained for nine million bpd of its crude.
Nigerian industry sources say Africa's largest producer, also an OPEC member, could immediately open the taps on 300,000 bpd of crude.
It was not made clear where the extra capacity would come from.
International oil companies operating in Nigeria have some 180,000 bpd of unused capacity in the Niger Delta that has been shut in for more than a year by ethnic tension and vandalism. But that is not thought likely to reopen in the short-term.
Nigeria says it is currently producing between 2.4 and 2.5 million bpd, and that it will boost capacity to 2.8 million bpd by the end of the year.
Constrained by transportation bottlenecks, Russian officials say only a modest boost to the leading non-OPEC producer's exports is possible in the medium term after strong growth for several years.
Russia's top energy official Viktor Khristenko said on Thursday he considered options for boosting exports to be very limited.
He said medium-term options to raise exports depended mainly upon the Baltic Pipeline system, which pipeline monopoly Transneft wants to expand by 150,000 bpd to one million bpd by the end of the year.
Other expansions of pipeline and port capapcity would take longer.
Analysts and industry sources expect Russia's production to hit 9.5 million bpd by the end of 2004, with exports hovering around four million bpd.
Non-OPEC Mexico has said it aims to increase exports to 1.95 million bpd from 1.88 million by the second half of 2004.
Energy Minister Felipe Calderon said on Wednesday the increase would not be immediate. "It's not something that can be done overnight," he said.
It is not clear how much spare capacity resides in the United Arab Emirates.
Newspapers in the OPEC member have cited the country's 2004 government yearbook to put total capacity at 2.63 million bpd, but the International Energy Agency puts UAE capacity at 2.45 million.
The IEA pegged UAE April production at 2.15 million bpd, implying that at least 300,000 bpd lay spare.
Kuwaiti Oil Minister Sheikh Ahmad al-Fahd al-Sabah said this month the OPEC member still had some surplus capacity, and that it was willing to use this to help cool prices.
He did not put a figure on this capacity though.
IEA estimates of 2.28 million bpd output in April and total capacity of 2.3 million bpd imply almost no room for increases.
A Kuwaiti official was quoted in the local press this week saying Kuwait was already pumping 2.4 million bpd.