The Organization of Petroleum Exporting Countries expects the combined cuts would reduce actual production by about 10 percent, or 2.5 million barrels a day.
OPEC agreed to the two-stage reduction in output to try to keep oil prices stable when warmer weather erodes demand in major importing countries.
The oil group has often urged its members to comply better with their agreed quotas, but its decision to make an additional cut in its official target of 24.5 million barrels was unexpected.
"As time goes on in the second quarter, we will see a drop in demand that will affect prices. If we don’t do anything, there will be oversupply in the second quarter of about 3 million barrels (a day)," OPEC president Purnomo Yusgiantoro told a news conference at a government-run convention center in Algiers.
Ministers said they believed their action would send a strong signal about OPEC’s willingness to be proactive in managing crude supplies.
"Everybody will know that the organization is serious, and we would like to have a stable market," said Libya’s representative, Abdulhafid Mahmoud Zlitni, speaking after a closed-door meeting at which the delegates ratified their output decision.
The planned April cut in OPEC’s formal output is unconditional, added Obaid Al-Nasseri, oil minister for the United Arab Emirates.
Oil prices rose. North Sea Brent crude for March delivery rose 93 cents to settle at $30.04 in London, while March contracts for light sweet U.S. crude were up $1.04 to settle at $33.87 on the New York Mercantile Exchange.
OPEC’s decision is "regrettable," but the U.S. economy is less vulnerable to higher energy prices now than in the past, U.S. Treasury Secretary John Snow said Tuesday.
"Any reduction of those quotas from my view would be regrettable," Snow told reporters during a visit to Florida.
The secretary said higher energy prices are an obstacle to U.S. economic growth because they act as a tax on consumers. Still, Snow said he didn’t expect higher oil prices to hurt the U.S. economic recovery.
"Fortunately, we are not as dependent on energy as we were 10, 20 or 30 years ago because energy is a smaller and smaller share of our economy," Snow said.
