Opec quotas held despite demand fears Opec, the oil producing cartel, left its output target unchanged, despite concerns about oversupply in the market and soft oil demand as the global economy continues to show signs of weakness. Ministers meeting in Vienna stuck with their ceiling of 30m barrels a day, which was set a year ago. Analysts, however, said Saudi Arabia, the group's largest producer, would likely cut production on its own if prices begin to fall. Figures released by Opec on Monday showed it had already cut its output to its lowest level for a year. In its final communiqué, Opec said the biggest challenge facing oil markets next year was "uncertainty surrounding the global economy, with the fragility of the Euro-zone remaining a major concern." It said that although world oil demand was forecast to rise slightly next year, this would be "more than offset by the projected increase in non-Opec supply." Because of that, projected demand for Opec crude would contract next year to 29.7m bpd, from 30.1m bpd this year. "Opec is in a potentially delicate situation here and it could all go badly wrong," said Neil Atkinson, director of energy research at Datamonitor. Unless something happens to disrupt supply, ... there's a serious risk that prices could fall quite sharply. A key factor in the increase in global supply is the huge surge in production of US unconventional oil, as techniques such as hydraulic fracturing or "fracking" open up new shale resources. Officials expect US output to rise by 760,000 bpd this year, the largest annual increase since the US started pumping crude commercially in 1859. Production is forecast to rise to more than 7m bpd next year, for the first time since 1992. Nigeria's oil minister Diezani Alison-Madueke said there was no oversupply at the moment, but added that "over the next 12 to 18 months there is concern that there might be - particularly with the shale oil that's coming in from the US." Speaking before closed-door talks began between ministers, she said US shale oil production would "have a major impact on Opec producing countries." The shale-fuelled surge in supply has coincided with a poor outlook for demand. The International Energy Agency said on Wednesday that oil demand growth would stay "relatively sluggish" throughout 2013, increasing by only 865,000 bpd on 2012 levels. That did, however, represent an upward revision on its previous estimate a month ago, partly reflecting a rebound in China. Brent crude was trading $1.33 higher at $109.34 a barrel on Wednesday. Mr Atkinson compared the current situation with early 1986, when global oil demand was weak, stocks were high and new supplies were coming on from the North Sea - in similar volumes to the unconventional oil now being pumped in the US. As crude fell to $10 a barrel, Opec was forced to repeatedly cut production to put a floor under prices - and in the process lost market share to non-Opec producers like the UK. Opec failed to reach agreement on another key issue - the choice of a new secretary-general, to replace Abdalla el-Badri, a Libyan who has been in the post for two three-year terms. Contenders from Iraq, Iran and Saudi Arabia vied for the post, but none garnered enough support. It was ultimately decided that Mr el-Badri should stay on for another year.