NEW YORK, March 17: World oil prices edged lower on Friday as traders digested the impact of a decision by the Opec cartel to keep its crude production levels steady. New York's main oil futures contract, light sweet crude for delivery in April, lost 44 cents to close at $57.11 a barrel.

It was a volatile session, with New York futures veering between a high of $58.29 a barrel and a low of 56.17.

In London, the price of Brent North Sea crude for May delivery retreated 38 cents to $60.30 a barrel.

Opec's agreement to leave production restraints unchanged was widely anticipated, but the impact of the decision is still being debated, Deutsche Bank analyst Adam Siemski in London said.

Crude futures had fallen on Thursday after the Organization of the Petroleum Exporting Countries kept its daily output target at 25.8 million barrels, arguing that global supply levels are healthy.

The market is stable, the market is healthy, we do not need to touch (output) at this time, Opec secretary-general Abdullah al-Badri told a press conference after a ministerial meeting in Vienna.

The 12-nation cartel had already cut production at its two previous meetings in October and December.

In its monthly report, Opec added that world oil demand would grow by 1.5 per cent in 2007, matching its forecasts in January and February.

Opec's only surprise was its announcement to meet in September, skipping an expected June meeting, analysts said. The cartel said its next meeting would be an ordinary session in Vienna on September 11.

The move suggested they are in no hurry to raise output again, said Tim Evans, a Citigroup analyst.

Crude oil prices began the week in negative territory on Monday as traders digested forecasts of warmer weather across the United States, which is the world's biggest energy consumer.

The market was also roiled by fresh turmoil on global equity markets and patchy US energy reserves.

Prices found some support after the International Energy Agency warned of a potential supply crunch in many industrialized nations during the first quarter of 2007.

Fimat analyst Mike Fitzpatrick said selling pressure could resume next week as the Opec decision plays out.

Since this outcome offered no new price support, participants may be a little disgruntled, since the cartel's compliance record, to date, has been inconsistent, he said.

There is a widespread belief that not every Opec member has abided by the previous decisions to cut output, which was taken in a bid to lift oil prices back up following a long slide from mid-2006 highs above $78 a barrel.

Fitzpatrick, however, noted there were also supportive factors for prices, such as supply constraints for US gasoline.

Continue to be mindful of the evolving dispute with Iran. It has the potential to provide significant price support to the whole complex, he added. -AFP