World oil prices rose slightly on Wednesday as OPEC members agreed as expected to hold the cartel's output, while the weekly US energy inventory report was broadly in line with forecasts.

New York's main contract, light sweet crude for April delivery rose 51 cents to 82.21 dollars a barrel.

London's Brent North Sea crude for May delivery was up 79 cents to 81.32 dollars per barrel.

OPEC, which pumps 40 percent of world crude, froze its output ceiling at a meeting in Vienna, against a backdrop of recovering oil prices and uncertainty over global economic prospects.

In a statement issued after a ministerial meeting in the Austrian capital, the Organization of Petroleum Exporting Countries said it "decided to maintain the current oil production ceiling unchanged."

Nevertheless, "given the uncertainty in the macroeconomic environment and world oil demand, the secretariat will continue to monitor closely developments in the months ahead," the statement said.

OPEC, which is marking its 50th anniversary this year, said it would review the economic situation at its next ordinary meeting in Vienna on October 14.

"We have to be very cautious because what we are seeing at this time, it's not really (economic) growth," OPEC Secretary General Abdalla Salem El-Badri told reporters at a news conference in the cartel's brand new headquarters.

"A lot of money is being thrown into the market and the growth (we're seeing at the moment) is because of the stimulus packages. China is having stimulus packages, the United State, Europe, Japan.

"And everyone is putting money into the economy so they can prevent this recession."

El-Badri said the main worry for OPEC was how it handles "the exit from those stimulus packages."

The decision not to alter its output ceiling -- which the cartel has now held unchanged for 15 months -- had been seen as a done deal.

In recent days, OPEC's 12 member countries have pointed to high oil inventories, low demand and recovering crude prices for reasons not to move.

The cartel's official production quota stands at of 24.84 million barrels per day.

The oil market was meanwhile unruffled by publication of the US government's weekly update on energy inventories.

The Department of Energy (DoE) revealed Wednesday that American crude reserves rose by one million barrels in the week ending March 12. That matched market expectations, according to analysts polled by Dow Jones Newswires.

Stockpiles of distillates, which include diesel and heating fuel, fell 1.5 million barrels. Analysts had predicted a one-million-barrel decline.

However, gasoline or petrol inventories sank by 1.7 million barrels, which was heavier than the 600,000-barrel drop pencilled in by analysts.

Oil prices had rebounded sharply on Tuesday as the US Federal Reserve held record low interest rates in the hope of stimulating a still fragile US recovery.