Brent crude oil fell more than $3 to a fresh four-year low under $75 a barrel on Thursday after OPEC decided not to cut production, despite a huge oversupply in world markets.
Asked whether the oil producer group had decided not to reduce production, Saudi Arabian Oil Minister Ali al-Naimi told reporters: "That is right."
Oil prices have fallen by more than a third since June as increasing production in North America from shale oil has overwhelmed demand at a time of sluggish global economic growth.
Ministers from the Organization of the Petroleum Exporting Countries had been discussing whether to agree a production cut at their meeting in Vienna.
Benchmark Brent futures were down by $2.96 a barrel at $74.79 by 1520 GMT, after hitting a low of $74.36, their lowest since August 2010.
U.S. crude was at $71.07, down $2.62.
"Oil prices are now completely in the hands of the market," Dominic Chirichella, director of New York-based Energy Management Institute, told Reuters Global Oil Forum.
Kuwaiti Oil Minister Ali Saleh al-Omair said there would be "no change" to OPEC's existing oil production target following the meeting.
The cartel will meet again in June next year, said an OPEC delegate. Ehsan Ul-Haq, senior oil market consultant at KBC Energy Economics, in Vienna for the OPEC meeting, said a KBC report expected oil prices stay under $80 a barrel.
"The probability of oil prices going below $70 a barrel is 20 percent, remaining in a range of $70-80 a barrel is 40 percent," he said.