London ? Sluggish demand from refiners and a surge in oil output from Iraq and Norway sent crude prices sliding by more than $3 a barrel last month, the International Energy Agency reported Tuesday.

The peak winter heating season in the northern hemisphere should help rebalance supply and demand in the fourth quarter despite the slow pace of global economic recovery, the energy watchdog said in its monthly oil market report.

The IEA, based in Paris, is the energy watchdog for the Organization for Economic Cooperation and Development, a group of rich, oil-importing nations.

Worldwide oil supplies rose by 1.6 percent in October to 78.27 million barrels a day. OPEC’s contribution to the increase “caught the market off guard,” particularly the growth of 570,000 barrels a day in Iraq’s output, the report said. Iraqi exports have risen sharply since September when Baghdad stopped imposing illegal surcharges on them.

Norwegian rigs resumed activity after interruptions for maintenance the previous month, adding 390,000 barrels a day to global supplies.

At the same time, worldwide demand was virtually unchanged from September. Demand for gasoline showed steady growth, but the jet fuel market remained depressed.

The IEA forecast a global demand this year of 76.7 million barrels per day.

A perceived relaxation of tensions in the Gulf led to a sell-off of oil futures contracts in October and contributed to the downward drift in crude prices.

However, prices for refined products such as gasoline and heating oil fell less sharply, suggesting that a tighter market for crude could lie ahead.