Fundamental factors do not justify the sharp drop in oil prices, OPEC Secretary-General Abdullah al-Badri said on Thursday, forecasting a price rebound by the second half of 2015.
"We are concerned but we are not panicking," he told reporters at a news conference on the group's 2014 World Oil Outlook.
"We don't see that much of change in fundamentals. The decline is 28 percent, it's a little bit too much," he said, adding the group was evaluating the situation to gauge how events might develop. OPEC meets on Nov 27 and Badri said OPEC had not invited any other producers to attend.
Brent crude futures have fallen 27 percent since the start of July and 12 percent in the last month.
"I think the price will rebound by the second half of next year. But I don't know by how much. This situation of low prices cannot continue," he said, adding speculation was playing a role in the price drop.
Badri had told reporters in September that he thought oil prices would come back up by the end of this year.
He said it was up to OPEC member countries to decide how to respond to the oil price drop. The next ministerial meeting is on Nov. 27.
OPEC's oil market share is set to be 5 percent smaller by 2018 as supply of U.S. shale oil grows faster than previously thought, giving the 12-member exporter group little comfort from rising world demand, its market outlook found.
Asked about the impact if oil prices stay low for a long time, Badri pointed to the heavy investments OPEC members were making in their energy sectors.
"If we stop this I am sure the supply will decline very soon and the price will shoot up and volatility will be causing the oil industry...a lot of problems," he said.
(Reporting by Michael Shields and Shadia Nasralla, editing by William Hardy)