OPEC's bitterly divided oil ministers have decided not to raise the cartel's overall production for the second half of the year in a bid to shore up shaky oil prices, the Iranian oil minister said Monday.

"There will not be any increase in production for the next six months, but negotiations are still going on about ceilings," Iran's Gholamreza Aghazadeh told reporters, indicating there still is a possibility of a reduction.Ministerial sources said earlier the Organization of Petroleum Exporting Countries informally agreed Sunday to maintain its first-half production ceiling of 15.06 million barrels a day because of a deep split over assigning new quotas to the 13-member nations.

Such a move probably would mean an initial drop of 30 cents to 40 cents a barrel, analysts suggested but then would lift oil prices to around $17.50 a barrel in the third quarter and $18.50 in the fourth.

Oil prices currently are hovering around $16 a barrel - below OPEC's official $18-a-barrel target.

Saudi Arabian Oil Minister Sheikh Hisham Nazer told reporters, "There will definitely be an agreement" Tuesday, when the midyear ministerial conference reconvenes at OPEC headquarters.

The ministers shunned the formal conference table Monday in favor of bilateral meetings aimed at resolving other issues.

Aghazadeh said the ministers were "not making progress" on the question of bringing maverick member Iraq back into the self-imposed OPEC production ceiling agreed upon in December.

Iraq boycotted the agreement and is seeking production parity with its Gulf war enemy Iran, which was allocated a quota of 2.4 million barrels a day. Iraq's lid is 1.6 million barrels a day, but Baghdad has been pumping about 2.6 million barrels a day.