Mozambique police raid opposition headquarters MAPUTO (Reuters) - Mozambican police raided the headquarters of the opposition Renamo party, arresting up to 15 people and firing teargas, the opposition and local media said on Thursday, fuelling tension before next year's election. Renamo's head of security, Osufo Madate, said a bullet grazed the stomach of one party member during Wednesday's raid, which he blamed on the ruling Frelimo party. "We have had enough," Madate told Reuters. We cannot stand by with our arms crossed while Frelimo attacks our people. We will retaliate. He confirmed some arrests, but not the 15 reported by Radio Mozambique. The incident is the latest flare-up between the two parties, enemies in a 16-year post-independence civil war in the mineral-rich southern African nation that subsided in the early 1990s. Renamo president Afonso Dhlakama briefly retreated to a camp in the secluded Gorongosa Mountains in November, threatening to set up a guerrilla training camp and kick off another war. A year ago police killed two men after storming Renamo offices in northern Mozambique. Although open hostilities are unlikely given Frelimo's political and military dominance since a shaky 1992 truce, tensions are bound to worry foreign mining firms exploring some of the world's largest untapped coal and natural gas reserves. The drama is not new. Neither are the actors. The only change is the intensity of the soundtrack," the O Pais paper said. Whenever there are electoral challenges in the country, there is a tendency to resuscitate the horror of war and violence. Major investors in Mozambique include Italy's Eni, New York-listed Anadarko, Brazil's Vale and London-listed Rio Tinto. Mozambique's offshore Rovuma gas field is believed to hold 150 trillion cubic feet of gas, enough to supply Germany, Britain, France and Italy for 15 years. Reporting by Marina Lopes; Editing by Alistair Lyon