FACTBOX-Which oil firms are affected by Niger Delta unrest?

(Reuters) - Nigeria's main militant group said on Monday it had sabotaged one of Chevron's crude oil pipeline junction points in the Niger Delta, the second attack in as many days.

Following are details on which firms have been affected by MEND's latest campaign and what they have said about production:

CHEVRON

The Movement for the Emancipation of the Niger Delta (MEND) said on July 6 it attacked Chevron's Okan manifold in southern Delta state.

The U.S. energy firm said on May 25 it had shut down approximately 100,000 barrels per day (bpd) of oil production from its swamp operations in Delta state following the first major strike in the militants' latest campaign.

MEND said that day it had sabotaged pipelines to flow stations at Alero Creek, Otunana, Abiteye, Makaraba and Dibi in Delta state.

MEND claimed on June 10 to have sabotaged Chevron's Otunana pumping station in Delta state but the military denied any such attack had occurred and that a fire at the facility, confirmed by Chevron, was a result of a systems failure.

On June 13, Chevron confirmed there was a breach on its Makaraba-Utonana-Abiteye pipeline and fire at its Makaraba Jacket 5 facility in Delta state but said output was unaffected as the infrastructure had already been shut down.

MEND said on June 15 it had attacked Chevron's Abiteye flow station.

ROYAL DUTCH SHELL

Shell has said the latest attacks have slashed output from its onshore facilities to 140,000 barrels per day (bpd), around half of what it was producing earlier this year.

MEND said on July 5 it had attacked a Shell oil well head in the Cawthorne Channel which is connected to the Bonny export terminal in Rivers state.

Shell said on June 29 it had shut in some production after reports of attacks, claimed by MEND, on two well clusters in its Estuary Field, near to its Forcados export terminal.

Shell had on June 17 extended a force majeure on its Forcados oil shipments for the rest of June and all of July. The measure, which frees it from contractual obligations, was first imposed in March after an attack on its trans-Escravos pipeline.

Shell said on June 25 it had shut down one of its pipeline valves at Krakrama manifold in its eastern operations in the Niger Delta after MEND claimed an attack on the Billie/Krakama pipeline in Rivers state.

The firm declined to say whether output was affected.