The oil-producing OPEC cartel has for the fourth straight month trimmed its estimate of world demand for oil for the rest of this year and in 2012.

The 12-nation Organization of the Petroleum Exporting Countries said Tuesday that the demand for oil will still grow this year and next, but not by as much as it had projected earlier. OPEC said the world demand will slow as global economies continue to weaken.

OPEC said its demand estimate is being reduced because of the sluggish U.S. economy, the world’s largest, as well as Europe’s governmental debt crisis and efforts by China and India to curb fuel consumption.

OPEC, which produces about a third of the world’s oil, said it now sees oil demand this year growing by less than a million barrels a day to just under 88 million barrels a day. That cuts 180,000 barrels a day from OPEC’s estimate a month ago. It cut 70,000 barrels a day from its 2012 estimate, but still predicts that the overall demand will increase by 1.2 million barrels.

With reduced demand, the price of oil has fallen in recent months — to about $84 a barrel on the New York market on Tuesday, down from a high this year of more than $116 in April.