The Movement for the Emancipation of the Niger Delta (MEND) said it attacked a Royal Dutch Shell oil pipeline and a Chevron-operated oilfield in the Niger Delta in the heaviest fighting there in two years. However, a military spokesman denied the militants had made an assault on Chevron, while a private security source said MEND had attacked but was repelled. The group, which is fighting for a bigger share of the region's oil wealth, has cut Nigeria's oil output by more than 20 percent since it began a campaign of violence two years ago.