June 22 (Bloomberg) -- A Nigerian militant group said this evening that it would unilaterally declare a ceasefire in the country's Niger Delta region ``effective 12 midnight on Tuesday, June 24.''

The Movement for the Emancipation of the Niger Delta, a rebel group known as MEND, made the announcement in an e-mailed statement this evening, citing spokesman Jomo Gbomo. The ceasefire will be observed ``until further notice,'' Gbomo said in the statement, and comes in response to an appeal ``by the Niger Delta elders to give peace and dialogue another chance.''

The ceasefire intention follows disruption to oil operations in Nigeria. Chevron Corp.'s Nigerian onshore oil output remained halted following an attack on a pipeline operated by the company, H. Odein Ajumogobia, the country's minister of state for petroleum, said today.

Chevron Nigeria's Abiteye-Olero pipeline was ``breached'' on June 19 in what was suspected to have been an act of sabotage, the San Ramon, California-based company said yesterday. About 120,000 barrels a day of crude have been halted by the attack, Agence France-Presse reported.

MEND had earlier said the Chevron pipeline was attacked by ``angry youths who we are now empowering with more powerful explosives and new techniques to destroy additional pipelines.''

Nigeria, Africa's second-biggest oil producer after Angola, is currently pumping about 1.8 million barrels a day, Ajumogobia told reporters in Jeddah, Saudi Arabia, where he was attending a meeting of oil producers and consumers. Rebels in the Niger Delta, which supplies all of the nation's crude, have sabotaged infrastructure to press their demand for a greater share of oil wealth and more political power.

Militant Action

Royal Dutch Shell Plc said on June 19 it shut down the Bonga oil field in Nigeria because of militant action, halting shipments of as much of 190,000 barrels a day.

Shell said June 20 it declared so-called force majeure on exports of Bonga crude for the remainder of June and July. Force majeure is a legal clause that allows producers to miss contracted deliveries because of circumstances beyond their control.

Continuing supply disruptions in Nigeria have contributed to the near doubling of prices in the last year. Crude oil for July delivery rose $2.69, or 2 percent, to $134.62 a barrel on the New York Mercantile Exchange on June 20. Futures climbed to a record $139.89 on June 16.

To contact the reporter on this story: Julie Ziegler in Lagos at jziegler@bloomberg.net; Paul Okolo in Lagos pokolo@bloomberg.net

Last Updated: June 22, 2008 17:01 EDT