Oil prices fluctuated slightly Monday after climbing close to $100 a barrel earlier in the session.
Light, sweet crude for April delivery was up 19 cents at $99 a barrel on the New York Mercantile Exchange, but was moving in and out of positive territory. It climbed as high as $99.70 a barrel earlier on supply concerns heightened by a Turkish military incursion into northern Iraq and warnings by Iran against further international sanctions
On Friday, the contract settled 58 cents, or 0.6 percent, higher at $98.81 a barrel.
Some analysts noted that some investors had invested heavily in crude, betting that prices will continue to rise, and that this was likely to contribute to volatility in the market.
In other Nymex trading, heating oil futures rose 0.01 cent to $2.7744 a gallon while gasoline prices were unchanged at $2.5416 a gallon.
Natural gas futures added 12.1 cents to $9.267 per 1,000 cubic feet.