UPDATE 4-Nigeria militant attack on Chevron shuts 100,000 bpd
* First major strike since military offensive
* Chevron says 100,000 bpd shut-in
* Oil infrastructure at continued risk
(Recasts, adds background, details)
LAGOS, May 25 (Reuters) - Nigerian militants launched their first major strike against the oil industry since the start of a 10-day old military offensive late on Sunday, bombing a Chevron (CVX.N) pipeline and shutting 100,000 barrels per day of output.
The Movement for the Emancipation of the Niger Delta (MEND) said in an email it had sabotaged pipelines to flow stations at Alero Creek, Otunana, Abiteye, Makaraba and Dibi feeding a Chevron facility in Delta state.
The U.S. energy firm confirmed one of its pipelines in the Abiteye area was breached on Sunday and said it had shut in production as a precautionary measure while checks were made.
"To protect the environment, the incident has led to the shut in of approximately 100,000 bpd production from swamp operations in Delta State," a Chevron spokesman said.
"The company is currently assessing the situation, while the incident has been reported to relevant government agencies."
The military began its biggest offensive for years 10 days ago, bombarding militant camps around Warri in Delta state from the air and sea and sending three battalions of soldiers to hunt down rebels believed to have fled into surrounding communities.
It said it could no longer "fold its hands" after attacks on soldiers, pipeline bombings and the hijacking of oil vessels, all of which have prevented Nigeria from reaching its full production potential in recent years.
The OPEC member's output peaked at around 2.4 million bpd before MEND burst onto the scene in early 2006 and knocked out almost a quarter of production in a matter of weeks.
Output has never fully recovered. Oil Minister Rilwanu Lukman told reporters at a G8 energy ministers' meeting in Rome on Monday that Africa's biggest exporter was currently pumping about 1.5-1.6 million bpd, roughly half its installed capacity.
