Oil ticked up above $70 a barrel on Friday after Nigerian rebels said they blew up a wellhead in a Royal Dutch Shell
The move followed a 2 percent gain on Thursday and put oil on course for a 4 percent gain this month, buoyed by prospects for an economic recovery that has lifted prices from below $40 over the past four months.
The release of the June consumer sentiment index by the Reuters/University of Michigan Surveys of Consumers at 7:55 a.m. EDT (1355 GMT) was expected to reflect a mildly improving outlook for the U.S. economy, auguring well for ailing world energy demand.
By 8:16 a.m. EDT (1216 GMT), benchmark August U.S. crude oil was up 3 cents per barrel at $70.26, having hit a high of $71.29, up $1.06. London Brent rose 2 cents to $69.80.
Nigeria's Movement for the Emancipation of the Niger Delta (MEND) said it attacked the wellhead in the Afremo oilfield because the military had gone on a punitive expedition in Delta state shortly after President Umaru Yar'Adua announced an amnesty offer for rebels.
Shell said it was investigating reports of an attack on its Afremo platform B facility, which had already been shut down following an attack on the Trans Escravos pipeline in February.
Afremo was one of the sites MEND also said it had attacked in a triple raid on Sunday. It described the field as being 14 miles from an export terminal through which crude oil from Shell's Forcados fields is pumped.
Nigerian security forces said they would halt fighting during a government amnesty period for militants from August 6 until October 4 and would also release suspected rebel leader Henry Okah, who is on trial for gun-running and treason, if he accepted the amnesty offer.
There's a lot of focus on the Nigerian situation, said oil broker Christopher Bellew at Bache Commodities in London. Talk of an amnesty helped bring the market off its earlier gains.
Pipeline bombings, attacks on oil and gas installations and the kidnapping of industry workers over the past three years have prevented Nigeria from pumping much above two thirds of its installed oil output capacity of 3 million barrels per day.
The intensity of recent attacks in Nigeria have taken the oil market by surprise and tightened West African oil supplies.
Iranian tension has also supported oil.
About 20 people have died in protests after Iran's June 12 presidential election, the most serious unrest since the 1979 Islamic revolution.
Fuelling oil's rise, Exxon Mobil
Firmer Asian stocks on the back of Wall Street's rally also lent support, with shares outside Japan <.MIAPJ0000PUS> climbing 1.4 percent and Japan's Nikkei <.N225> up 0.8 percent. <.T>
European shares rose <.EU>.
The Reuters/University of Michigan final June consumer sentiment index, due at 7:55 a.m. EDT (1355 GMT), is expected to show a reading of 69.0 compared with 68.7 in the May report, a Reuters poll of economists showed.
(Additional reporting by Jennifer Tan; editing by Anthony Barker)