By Andrew Beatty PANAMA CITY, Aug 16 (Reuters) - Police shot dead a Panamanian trade union activist on Thursday, a union official said, the second death this week as clashes between rival unions turn increasingly violent. Luis Arguelles, 25, a member of the left-wing Suntrac construction union, was shot by police during a confrontation between Suntrac members and government-backed union groups, Suntrac official Saul Mendez told Reuters. The shooting on Viveros, an island popular with tourists in the Bay of Panama, came two days after another Suntrac member was shot dead, and Justice Minister Olga Golcher said the government would open an investigation into both deaths. Clashes have intensified in recent weeks between Suntrac, which opponents say has political aspirations driven by its links to Venezuela's leftist leader, Hugo Chavez, and so-called "yellow unions," which Suntrac says the government set up to stifle dissent in Panama's booming building industry. Suntrac has long been pushing for better pay and working conditions amid a surge in building site accidents. Television images of Thursday's confrontation showed police standing by some two dozen union activists fighting with sticks and stones, and a gunshot was heard. On Tuesday, another Suntrac member, 36-year-old Osvaldo Lorenzo, was shot by members of a rival union in the town of Chilibre in the province of Panama that contains Panama City. Suntrac later announced a 24-hour strike for next Tuesday, potentially affecting up to 300 building projects. Walter Medrano, head of Panama's Chamber of Construction, appealed for calm and dialogue to prevent further conflict. But Suntrac leaders said the government was trying to intimidate it. Thursday's shooting came as the government closed public schools in the capital and surrounding areas for the day, saying intelligence reports pointed to a threat against civilians that could put children at risk if they went to school. It was not clear whether the threat was related to the union clashes.
