Tribal violence in the oil producing Niger delta region has left at least four more dead. Some ten percent of the nations oil production remains shut down because of the armed bands roaming the area. Six months ago, some 30 percent of the nations oil export capacity was shut down. But the army has sent more troops in the area in an attempt to suppress the tribal unrest. This has proved difficult, as the armed groups are basically criminal gangs fighting over territory and lucrative smuggling rackets.