South American leaders have threatened to pull out of a scheduled EU-Latin American summit in Spain if Honduras President Porfirio Lobo attends. Leaders of the 12-nation South American Unasur bloc, including Venezuela's Hugo Chavez and Brazil's Luiz Inacio Lula da Silva, urged Spain to not invite Mr Lobo. The Honduran leader was voted into power last year, following a coup which was denounced across Latin America. Regional powers expressed their support for ousted President Manuel Zelaya. Earlier this week the Spanish government, which currently holds the EU presidency, invited the Honduran leader to the EU-Latin America summit, scheduled to begin on 18 May. The Unasur bloc was formed nearly two years ago to boost unity among the region's powers and counterbalance the perceived influence of the US.