The average crude oil prices of the Organization of Petroleum Exporting Countries (OPEC) dipped to 65.06 U.S. dollars per barrel last Friday, 1.04 U.S. dollars down from the previous day, the cartel's secretariat said on Monday.

The OPEC oil prices reached a historic high of 68.40 U.S. dollars per barrel last Tuesday, and then dropped an average of 3.34 U.S. dollars per barrel in the following three days.

The drop was primarily due to the unexpected increase of the oil stock in the United States, the figure for which was released by the U.S. Energy Department in an Energy Report last Wednesday.

The gasoline stock added 2.1 million barrels last week, which was the first increase since February. Meanwhile, the crude oil stock of the United States also rose by 1.7 million barrels.

OPEC Weekly average crude oil prices hit 66.78 U.S. dollars per barrel, up by 0.34 U.S. dollars from the previous week.

Market analysts believed U.S. refineries could provide more fuel oil to the market, and meet the peak demand in summer.

They predicted that the oil prices could drop further in the coming week, but the fears in the market over the worsening of Iran's nuclear issue still could not be mitigated.

"If Iran's nuclear issue deteriorates again, the oil prices will hit a new record," warned the analysts in Vienna.

Freign ministers from China, the United States, Russia, Britain, France and Germany held a conference on Iran's nuclear issue in New York on Monday, in order to exchange their views. Its results would affect the development of the oil prices, said the analysts.

Iran is OPEC's No. 2 producer next to Saudi Arabia, with an output of 4 million barrels per day, and its daily export figure stands at 2.4 million barrels.

Source: Xinhua