Feb. 20 (Bloomberg) -- Crude oil rose after rebel attacks in Nigeria cut output from Africa's largest producer by almost 20 percent and militants threatened further assaults.

Royal Dutch Shell Plc said yesterday it had shut 455,000 barrels of a day of production after rebels attacked an oil terminal and pipeline, and kidnapped nine foreign oil workers. Nigeria pumps about 2.4 million barrels a day, or almost 3 percent of global output.

``The situation in Nigeria is likely to remain volatile for some time,'' said Dariusz Kowalczyk, senior investment strategist at CFC Seymour Ltd., a Hong Kong-based securities firm. ``Prices should rise because of disruptions in supply.''

Crude oil for April delivery rose 1.9 percent to $61.05 a barrel in electronic trading on London's ICE Futures exchange. The contract traded at $60.90 at 10:34 a.m. Singapore time, 30 percent higher than a year ago. The New York Mercantile Exchange, the world's largest energy market, is closed today.

In Japan, oil for July delivery rose as much as 2.7 percent to 43,200 yen a kiloliter on the Tokyo Commodity Exchange. That's equal to $58.14 a barrel. It traded at 43,170 yen at 11:00 a.m. in Tokyo.

Oil prices have tripled since 2001 as global demand, led by China and the U.S., has risen faster than production. Oil in New York has fallen 13 percent in the past four weeks as gains in U.S. inventories eased supply concerns.

The militant Movement for Emancipation of the Niger Delta said it attacked Shell's Forcados export terminal, the 115,000- barrel-a-day EA field and a pipeline in the Chanomi Creek area. Shell can't say when the Forcados terminal will reopen, London- based spokeswoman Caroline Wittgen said by telephone yesterday.

`Fresh Targets'

The hostages, employees of Willbros Group Inc., are citizens of the U.S., U.K., Egypt, Thailand and the Philippines, the company said yesterday. The hostages are in good health, Jomo Gbomo, a self-described spokesman for the militants said yesterday in an e-mailed response to questions.

``Fresh targets will be hit shortly,'' Gbomo said. ``There is no shortage of things to destroy.''

Nigeria, which is the fifth-biggest supplier to the U.S., produces low-sulfur, or sweet, crude oil, prized by refiners for the proportion of high-value gasoline it yields. Shell, based in The Hague and the world's third-biggest oil company, produces about half of Nigeria's output.

The Niger Delta movement has targeted Shell installations after alleging the company allowed an airstrip it operates to be used for a Nigerian Air Force helicopter attack on villagers in the region. Shell said it could neither confirm nor deny the field had been used. The Nigerian government said the helicopters were used to disable barges engaged in oil smuggling.

`Major Setback'

``The situation in Nigeria is a major setback for the global oil market,'' said Gal Luft, executive director at the Institute for the Analysis of Global Security in Washington. ``This is particularly bad since Nigeria is an important source of light, sweet crude, the most desirable of all the crudes.''

Iranian officials left for Moscow yesterday to discuss to a Russian proposal aimed at breaking the deadlock over the Islamic Republic's nuclear research program. Oil rose to $69.20 last month, its highest this year, on concern that the dispute may prompt Iran, OPEC's second-largest exporter to cut shipments.

The Russian government is proposing to carry out uranium enrichment for Iran, a compromise designed to allay concerns about the country developing nuclear weapons while guaranteeing Iran access to nuclear fuel. Iran's President Mahmoud Ahmadinejad on Feb. 11 expressed doubts on the proposal.

Vienna

The Moscow talks take place two weeks before the United Nations' nuclear watchdog meets in Vienna to decide whether to ask the UN Security Council to take action against Iran. The International Atomic Energy Agency voted on Feb. 4 to refer Iran, the Middle East's second-largest oil producer, to the Security Council for possible censure or sanctions.

``A sign of cooperation with the Russians would help relieve the tension in the market,'' said Hiroyuki Kikukawa, deputy general manager at Nihon Unicom Corp. in Tokyo.

The Nigerian shutdowns may prompt the Organization of Petroleum Exporting Countries, the 11-member group that pumps about 40 percent of the world's oil, to decide against cutting production when it meets next month in Vienna, analysts said. OPEC typically cuts output in the second quarter as demand falls after the end of winter in the U.S., Europe and Asia.

``If the 400,000 were to be shut down for a significant period of time, then OPEC would have to reassess what they were going to do at the meeting,'' said Adam Sieminski, chief energy economist at Deutsche Bank AG said yesterday.

Qatar Oil Minister Abdullah bin Hamad al-Attiyah said yesterday OPEC still may cut production by as much as 1 million barrels a day from April 1.

To contact the reporter on this story: Will Kennedy in Singapore at wkennedy3@bloomberg.net .