VIENNA, Austria — OPEC oil ministers agreed today to trim overall output by more than 500,000 barrels a day in a compromise meant to avoid new turmoil in crude markets while seeking to bolster falling prices.

The news sent oil prices rising. Light, sweet crude for October delivery rose 97 cents to $104.23 a barrel in electronic trading on the New York Mercantile Exchange.

The OPEC announcement reflected the organization's efforts to cover all bases in an oil market that saw prices spike to a record high just short of $150 a barrel in July, only to shed nearly 30 percent off those peaks.

Oil prices had lost more ground Tuesday ahead of the decision, falling $3.08 to settle at $103.26 on the Nymex, the lowest settlement price since April 1.

A statement issued by the Organization of Petroleum Exporting Countries issued after oil ministers ended their meeting early Wednesday said the organization agreed to produce 28.8 million barrels a day. OPEC President Chakib Khelil said that quota in effect meant that member countries had agreed to cut back 520,000 barrels a day in production over the established quota.

Saudi Arabia alone accounts for more than that amount of output over its official quota — all members of the 13-nation OPEC have such formal production limits allotted to them except violence-torn Iraq. But Khelil said that the cutbacks in overproduction would apply proportionally to all OPEC members bound by quotas.

OPEC overall regularly churns out oil above the organization's overall quota, last set in November at 27.3 million barrels a day, and it remained unclear whether group members would abide by the decision to keep to their limits.

Still, the decision could have the psychological effect of steadying eroding prices at or above the $100 mark, the red line for many OPEC nations concerned about their rapid loss of revenue in recent months.

While the new production limit of 28.8 million barrels a day is above that set in November, the statement said it reflected adjustments to include new members Angola and Ecuador and exclude Iraq, as well as Indonesia, which used the Vienna meeting to announce it was suspending its full membership.