(Adds death toll, soldiers patrolling, paragraphs 1,5,6) By Austin Ekeinde PORT HARCOURT, Aug 2 (Reuters) - A turf war between rival gangs in Nigeria's Niger Delta has spread to the main oil city of Port Harcourt, with sporadic gunbattles in its waterfront slums killing at least three people, witnesses said on Saturday. Fighters from one militant faction in the delta arrived in speedboats late on Friday to attack a rival gang and bursts of intense gunfire were reported in the heavily populated shanty neighbourhoods of Bundu, Dockyard and Yam Zone, residents said. Police commissioner Bala Hassan said a joint military task force intervened to try to repel the attackers. "Considering the intensity of the fighting last night, it is possible that some people were killed among the militants," Hassan told Reuters. Residents in the Dockyard neighbourhood said the bodies of at least three civilians had been removed by family members for burial. Soldiers in pick-up trucks patrolled on Saturday as those with somewhere else to shelter packed up and left. "We don't know when they'll attack again," one resident said, asking not to be named. The violence underscores the worsening security situation in the delta, the hub of Nigeria's 2 million barrel-per-day oil industry, where unrest has shut down around a fifth of output and helped push global energy prices to record highs. A private security source working in the oil industry said the clashes were a continuation of fighting which broke out late on Tuesday between two rival militant factions at Abonnema, around 14 km (9 miles) west of Port Harcourt. Two militants, a soldier and a civilian hit by a stray bullet were killed in that fighting. OIL INDUSTRY HUB Friday's violence marked the first serious clashes between rival militant factions inside Port Harcourt since last August, when up to 40 people died in days of street battles between troops with rocket launchers and heavily armed gangsters. The government imposed a dusk-to-dawn curfew on the city at the time, as young men with assault rifles, dynamite and knives invaded different districts and troops fought them off with helicopter gunships. Port Harcourt is the biggest city in the Niger Delta and oil companies including Royal Dutch Shell <RDSa.L> have offices there. It is also home to two of Nigeria's four oil refineries. Insecurity in the vast wetlands region surged in early 2006 when militants complaining of poverty started blowing up oil pipelines and kidnapping foreign oil workers. Criminal gangs have taken advantage of the breakdown in law and order and the instability has become as much about control of a lucrative trade in stolen oil and abductions for ransom as about political struggle. Security sources said they believed the clashes were between fighters loyal to two rival factional leaders -- Farah (eds: one word) and Soboma George -- with links to the main militant group the Movement for the Emancipation of the Niger Delta (MEND). MEND blew up parts of a major pipeline belonging to Royal Dutch Shell on Monday, forcing the Anglo-Dutch giant to shut down some production and warn that it may not be able to meet all of its export obligations in the coming months. The group has not commented on the clashes. (For full Reuters Africa coverage and to have your say on the top issues, visit: http://africa.reuters.com/ ) (Writing by Nick Tattersall in Lagos; editing by Andrew Roche)
REFILE - UPDATING CAPTION A file photo taken in April 2008 shows Berge Sisar, a liquefied petroleum gas (LPG) tanker from which gunmen kidnapped eight foreign oil workers off Nigeria's Niger ...
