Oil prices rose by nearly $1 a barrel Monday after Edmund Daukoru, the Nigerian oil minister and president of the Organization of the Petroleum Exporting Countries, said the oil cartel may need to cut its output further and as armed protesters shut down one of his country's oil facilities.

"The market is clearly oversupplied, clearly oversupplied," Daukoru told reporters during a visit to South Korea.

In Nigeria, government officials said armed protesters overran and shut down an oil facility run by Agip, a subsidiary of Italian energy company ENI SpA.

Light, sweet crude for December delivery climbed 88 cents to settle at $60.02 a barrel on the New York Mercantile Exchange. December Brent crude on London's ICE Futures exchange climbed 60 cents to settle at $59.75 a barrel.

Global Insight energy analyst Kevin Lindemer said the oil market "has pretty much bottomed out" due to the end of the autumn shoulder season, in which there is a lull in demand before winter, and the fact that OPEC recently announced a 1.2 million barrel a day output cut.

Lindemer said prices could fall further if winter is warmer than usual or if economic growth slows more than expected.

Still, some OPEC members are concerned that prices have already fallen far enough from their summer peak of near $80 a barrel.

Daukoru described the current price of oil as low. Regarding OPEC's decision last month to cut production effective Nov. 1, he said the effects of the reduced output have yet to be seen but would be soon.

Daukoru told reporters that when OPEC meets in December members will discuss production, "but it looks as if some further mopping up will be necessary."

Oil prices have retreated significantly from their summertime high, trading in a range of about $57 to $61 a barrel over the past month as traders look for clues to demand in weather and economic forecasts and weigh them against OPEC's plans to curb supplies.

On Friday, a bomb hoax at a huge BP PLC refinery in Whiting, Ind., rattled the market. Prices also jumped after U.S. diplomats warned that militants in Nigeria were preparing a major new wave of attacks and kidnappings across the country's oil-rich delta region.

On Monday, Nigerian protesters invaded an oil pumping station in the southern state of Bayelsa and forced workers to shut it down, said Joshua Benamesia, a security aide to the state governor.

Since the beginning of the year, militants have taken dozens of oil workers in the southern oil region hostage. The violence has pared about 25 percent from Nigeria's normal 2.5 million barrel daily production.

U.S. crude oil inventories rose by 2 million barrels, to 334.3 million barrels, during the week ended Oct. 27, the U.S. Energy Information Administration said. Demand is currently low because winter in the Northern Hemisphere has yet to set in.

Nymex heating oil futures climbed 4.09 cents to settle at $1.7184 a gallon, while gasoline futures edged 2.21 cents higher to $1.529 a gallon. Natural gas futures dropped 39.4 cents to settle at $7.49 per million British Thermal Units.