The weekly average price of the Organization of Petroleum Exporting Countries (OPEC), which remained weak last week, dropped slightly by 0.34 U.S. dollars to 109.25 dollars per barrel, the Vienna-based cartel said Monday.

The global economic growth including the U.S. remains weak, and the expectation on the European Central Bank's (ECB) assistance to the euro zone counties with high debt is also doomed.

The lack of driving of the economic growth leads to a weak crude oil market, which suppresses a sharp rise in oil prices.

The figures released by the U.S. Energy Department on last Wednesday showed that, until the first week of this month, both its crude oil inventories and refined oil inventories have increased to different degrees, which imposed further pressure on the international oil price.

In addition, the Standard & Poor's Ratings Services last week placed its long-term sovereign ratings on 15 members of the euro zone including Germany and France on "Credit Watch with negative."

Despite agreement at the EU summit on last Thursday and Friday to forge a "fiscal compact" in the Europe, doubts remain for an effective solution against European debt crisis.

OPEC ministerial meeting will be held in Vienna on Wednesday to discuss its future oil production quota. Currently, there is message from OPEC that it is unnecessary to increase crude oil output. It is therefore expected that there is possibility to keep the production level unchanged in the meeting.

An unchanged OPEC production volume might stimulate the oil prices to a certain extent.