OPEC: Rivals' oil supply growth will slow

The Organization of Petroleum-Exporting Countries (OPEC) reduced its forecasts for non-OPEC oil supply growth in 2015 on Thursday, indicating that its apparent strategy of putting pressure on its American rivals could be working.

In its monthly report, published Thursday, the group of 12 oil-producing nations also said demand for the oil it produced would be higher than previously thought, at 29.3 million barrels per day (mb/d).

OPEC – which includes Saudi Arabia, Iran, Libya, Nigeria and Venezuela and others as members -- has become well known over the last year for its refusal to reduce production, despite tumbling global oil prices amid a glut in supply.


Oil pumps in operation at an oilfield near central Los Angeles.
Mark Ralston | AFP | Getty Images
Oil pumps in operation at an oilfield near central Los Angeles.

The price of benchmark Brent crude oil has fallen from a high of $114 a barrel in June last year to trade around $62.30, but OPEC has been seemingly content to watch the price fall without cutting production in a bid to support prices.

The move has been widely seen as an attempt by the old guard of oil producers to put pressure on the new era of shale oil producers in the U.S. and Canada – where production costs are higher.

Read MoreOil demand seen rising, but Iran calls for cut

OPEC said it expected non-OPEC oil supply this year to grow by just 680,000 barrels per day (b/d) – down from its previous forecast of 850,000 b/d.

"U.S. tight oil and Canadian oil sands output are expected to see lower growth following the recent strong declines in rig counts," the report said.

U.S. production certainly appears to be slowing. U.S. oil prices jumped on Wednesday after data showed U.S. inventories had built up more slowly than expected.

Talks between major oil producers also triggered speculation of production cuts, even though most analysts said these were unlikely, according to a Reuters report.

On Thursday, oil rose more than 3 percent, pushing Brent crude to a 2015 high above $63 per barrel on increasing evidence that U.S. production is peaking. Following OPEC's report and production figures, however, the price fell back to $62.28.

Data within the report showed a marked increase in crude oil production in Saudi Arabia, Iraq and Libya in March from the previous month. In Saudi, for example, the amount of barrels produced a day rose from 9.6 mb/d in February to 10.01 m/bd in March.

OPEC laid the blame for price declines at the door of other oil producers, saying that the supply glut since June 2014 was "compounded by production increases in the U.S. and elsewhere."

Read MoreEIA lowers US crude oil production growth forecast

Referring to its own "Reference Basket" index – a weighted average of prices for petroleum blends produced by OPEC countries – it said the index had fallen in March by $1.60 to $52.46 a barrel, as "the market refocused on the oversupply situation, which was further impacted by production increases in many areas, while demand remained subdued."

However, OPEC continues to show no sign of cutting production itself. Crude produced by the group increased by 810,000 b/d in March, to average 30.79 mb/d, it said, citing secondary sources.

OPEC slams oil producers' 'go-it-alone' attitudes

OPEC left its global oil demand growth forecast unchanged at 1.17 mb/d in 2015, with close to two-thirds of this growth coming from China, elsewhere in Asia and the Middle East.

Looking at global economic growth forecasts and the potential for a drop in demand, the report said "the most recent softening trend in the U.S. and some major emerging markets will need to be carefully monitored."

- By CNBC's Holly Ellyatt, follow her on Twitter @HollyEllyatt.