Royal Dutch Shell PLC spokesman Precious Okolobo said Saturday that attackers hit a flow station belonging to Shell's joint venture in southern Nigeria and that some oil production had been shut down.
He gave no further details. Flow stations are intersections for pipelines carrying oil from wells to export terminals.
"The geopolitical news (out of Nigeria) is supportive of oil pricing and causes investors to come back into oil," said Victor Shum, an analyst with Purvin & Gertz in Singapore. However, "the strengthening dollar has capped further gains in oil," he said.
Light, sweet crude for June delivery on the New York Mercantile Exchange rose 47 cents to $116.79 a barrel in electronic trading by afternoon in Europe. The contract rose $3.80 to settle at $116.32 a barrel on Friday.
Crude futures soared Friday after Turkish airstrikes on Kurdish rebel bases in Iraq injected supply concerns into the market.
Also supporting oil prices were concerns about Iran after Supreme Leader Ayatollah Ali Khamenei said Sunday that his country will not bend to international pressure and give up its nuclear program. Iran is the second largest producer in the Organization of Petroleum Exporting Countries.
When conflict breaks out or political tensions rise in the Middle East, investors often buy oil on concerns that supplies will be disrupted.
"The market is supported by strong commodity index fund buying that happened on Friday, driven primarily by a belief that there would be supply issues in the long term," Shum said.
At the same time, an employment report from the U.S. Labor Department also gave investors reason to be optimistic about the U.S. economy — and raised the floor on prices. The U.S. is the world's largest consumer of oil and any drop in demand there can have a global impact on prices.
Vienna's JBC Energy described the relatively positive employment figures as "the main bullish factor in the market."
"Positive news on the U.S. economy eased concerns about a recession and made further (U.S. interest) rate cuts ... unlikely," said Monday's JBC newsletter. "Theoretically, this would decrease the amount of money invested in oil as a hedge for the falling dollar."
Oil prices dropped to nearly $110 a barrel on Thursday, helped by the rising U.S. dollar, which now stands above 105 against the yen and near 1.55 against the euro. Both levels are significantly above record lows the dollar hit last month and in March against the currencies.
A rising dollar undercuts the appeal of commodities such as oil as a hedge against inflation, and makes oil more expensive to investors overseas.
In other Nymex trading, heating oil futures added nearly a penny to $3.2270 a gallon while gasoline prices were nearly flat at $2.9664 gallon. Natural gas futures rose more than 11 cents to $10.88 per 1,000 cubic feet.
Brent crude futures rose 65 cents to $115.21 on London's ICE exchange.