By Fayen Wong
U.S. light crude for June delivery CLc1 rose 22 cents to $116.54 a barrel by 0605 GMT.
London Brent crude LCOc1 gained 20 cents to $114.76.
"Prices are still very high, considering the fundamentals and that we are now in a seasonal low in demand. Geopolitics and supply concerns are the key driver," said Gerard Burg, a Melbourne-based analyst at National Australian Bank.
Royal Dutch Shell was forced to shut more of its production in Nigeria after a militant attack on Saturday on a flowstation in the oil-rich Niger Delta, where local militants have stepped up a campaign of violence.
"A few oil delivery lines are affected and some oil has spilled into the environment," a Shell spokesman said. Recent violence has already knocked 164,000 barrels a day of Shell production in Nigeria.
In the Middle East, Iran's Foreign Ministry said on Monday it will not agree to any package of incentives offered by world powers that violate Iran's nuclear rights.
The comments come just three days after major powers said they would make a new offer to convince the Islamic Republic to halt its nuclear plans.
Renewed clashes between Turkey and Kurdish rebels in northern Iraq also lent support to oil prices.
The Turkish army said on Saturday that it killed more than 150 Kurdish PKK fighters in air strikes in northern Iraq last week, but the rebel group denied this and security forces in the region also expressed scepticism.
U.S. oil rose $3.80 to settle at $116.32 on Friday, bolstered by a U.S. government report that showed the economy lost only 20,000 jobs in April, a quarter the number economists had expected. Surprisingly strong U.S. factory order data improved sentiment further.
The gains followed three days of losses amid concerns that economic weakness in the United States would dent world oil demand.
Analysts said traders were now waiting for a survey later in the session on the U.S. service sector.
Crude oil speculators on the New York Mercantile Exchange cut net long positions last week, according to data from the Commodity Futures Trading Commission released on Friday.
Net crude long positions fell to 53,311 in the week to April 29, down from 70,562 in the week to April 22. (Editing by Ben Tan)
