Oil ministers of eight OPEC countries concluded three days of talks Saturday but failed to agree on a new production ceiling that would have facilitated attempts to boost oil prices by cutting excess output.

The eight members of the Organization of Petroleum Exporting Countries' price and long-term strategy committees called for a new meeting Nov. 17 in Vienna after failing to produce a framework for restoring production restraints.OPEC Secretary-general Subroto of Indonesia told reporters that "several proposals" for reducing production levels were under study and stressed that any new accord would be signed by all 13 members, indicating that Iraq would rejoin the quota system it left in mid-1986.

Subroto conceded that oil prices were likely to tumble following the committees' failure to reach a consensus on how to obtain OPEC's target price of $18 a barrel.

"Tomorrow the prices will go down. OK, they'll go down," Subroto said.

Oil prices rose slightly in the weeks leading up to the meeting, which was called in hopes of halting the recent plunge in oil prices largely caused by excess pumping by OPEC countries.

Subroto declined to provide figures for the proposed output levels, but several sources close to OPEC said 18.5 million to 19 million barrels a day was the most likely range for negotiations with the five other OPEC countries.

In opening talks Thursday, Subroto said he might call an extraordinary meeting before OPEC's scheduled Nov. 21 plenary conference in Vienna if the ministers in Madrid agreed on a new quota system. Iraq gave a clear indication Saturday it was willing to rejoin new production restraints.

"We are working for a 13-member agreement (on quotas)," Iraqi oil minister Issam Abdul Raheem al-Chalabi said, smiling broadly.

The Iraqi minister declined to give more specifics when asked about Iraq's demand for an equal output ceiling with arch enemy Iran.