UPDATE 2-Chevron declares Nigeria oil exports force majeure

(Recasts with force majeure declaration)

LAGOS, Nov 18 (Reuters) - U.S. energy giant Chevron (CVX.N) declared a force majeure in Nigeria on Tuesday after a main supply pipeline to its Escravos export terminal was sabotaged last week, forcing it to shut in around 90,000 barrels per day.

"Chevron Nigeria Limited (CNL) ... confirms that it has declared a force majeure effective November 18 through December 31, 2008," the company said in a statement.

It said onshore production was shut in in Delta state last Friday.

"Repair plans are being prepared and it would be premature to estimate completion time," it said.

Delta state is one of three main states in the Niger Delta, a network of mangrove creeks which are home to Africa's biggest oil and gas industry. Attacks by militants and criminal gangs have cut oil output in the region by a fifth since early 2006.

The pipeline, which feeds into the Chevron-operated Escravos export terminal in Delta state, was hit in Abiteye, where community members have attacked oil facilities in the past.

Armed youths blew up the Abiteye-Olero pipeline in June, forcing Chevron to cut around 120,000 bpd for nearly a month.

Chevron operates onshore in Nigeria in a joint venture with state-run oil firm the Nigerian National Petroleum Corp (NNPC). Chevron holds 40 percent while NNPC holds 60 percent. (Reporting by Nick Tattersall; editing by James Jukwey)