Sept 21 (Reuters) - Militants in Nigeria's oil-producing Niger Delta began a unilateral ceasefire on Sunday after a week of the most intense attacks for years on the oil industry in Africa's top producer.

Following are details on the facilities the main militant Movement for the Emancipation of the Niger Delta (MEND) claims to have attacked over the past week and what the operators have said.

PRODUCTION IMPACT

Royal Dutch Shell <RDSa.L>, which operates facilities in the Niger Delta through its SPDC joint venture with state oil firm NNPC, declared force majeure late on Friday on Bonny Light oil shipments because of the unrest.

The move, which frees it from contractual obligations, comes in addition to an earlier force majeure declared as a result of attacks on a key pipeline in July.

With so many attacks on varied locations, coming on top of repair work already being carried out on facilities across the delta, it is difficult to give precise figures for the production impact.

Shell has given no figures.

Nigerian government officials say oil output from Nigeria, the world's eighth biggest exporter, has fallen by 150,000 barrels per day over the past week and estimate the country's production at 1.95 million barrels per day.

OIL PIPELINE AT BUGUMA FRONT

MEND said they had attacked a major pipeline operated by Shell at Buguma Front in the Asari Toru local government area of Rivers state late on Friday, Sept. 19.

Shell said it was investigating reports of an attack on a pipeline belonging to its SPDC joint venture, but gave no further details.

OIL PIPELINE AT CAWTHORNE CHANNEL

MEND said its fighters had blown up a major pipeline operated by Shell at the Elem-Kalabari Cawthorne Channel axis in Rivers state late on Thursday, Sept. 18.

Shell said it was continuing to check its SPDC joint venture facilities for possible damage but gave no further details.

OIL PIPELINE AT RUMUEKPE

MEND said it had blown up a crude oil trunk pipeline which it believed belonged to both Agip and Shell on Wednesday, Sept. 17.

Shell said it had no reports of its SPDC joint venture pipeline at Rumuekpe being attacked.

ORUBIRI FLOW STATION

MEND said its fighters, in a new alliance with the Niger Delta Volunteer Force (NDVF), attacked and destroyed the Orubiri flow station belonging to SPDC on Tuesday, Sept. 16.

Shell confirmed a houseboat and station guard hut at Orubiri flow station were attacked but gave no further details. It also said a section of the Greater Port Harcourt Swamp Line was attacked on Sept. 16.

OIL PIPELINE AT BAKANA FRONT

MEND said it had blown up a crude oil pipeline at Bakana Front in Degema local government area in Rivers state operated by Shell late on Monday Sept 15.

There was no independent verification.

ALAKIRI FLOW STATION

MEND said its fighters stormed the Alakiri flow station operated by Shell in the early hours of Monday, Sept. 15 and set fire to the facility.

Shell confirmed its flow station, gas plant and field logistics base at Alakiri were attacked by gunmen. It said a station guard and an SPDC staff member were killed. It said three people were being treated for wounds and that it was reducing staff levels at some facilities as a precaution.

DECLARATION OF "OIL WAR"

MEND declared an "oil war" on Sept. 14 after what it said was an assault by the navy and air force on one of its positions in the Niger Delta.

It said it had attacked energy industry facilities including the Soku gas plant and a Chevron oil platform, and blown up the Nembe Creek crude oil trunk line at several points.

There was no independent verification of attacks on those specific facilities.

(Writing by Nick Tattersall; Editing by Mark Trevelyan)

AlertNet news is provided by