Security was pumped up in the crime-ridden city of Rio de Janeiro as Argentine President Nestor Kirchner arrived on Wednesday (January 17), on the eve of the two-day Mercosur summit. Rio, where gangs have recently been blamed for 19 killings, put an additional 500 elite federal policemen on the streets. The federal forces patrolled the main highways leading into the city to protect the chiefs of state as they arrive from the unsafe airport area. Even a naval ship was anchored in the waters near the Copacabana hotel where the summit will take place. The summit of presidents from the South American Mercosur trade bloc, which will be attended by regional leaders including Venezuela's Hugo Chavez, will be held on Thursday (January 18) and Friday (January 19). Bolivia, which nationalised much of its natural gas industry last year, is seeking full membership in the group. President Evo Morales is expected to arrive early on Thursday along with Chavez, who only recently joined the trade bloc. Amid Chavez's talks of nationalising its giant oil industry, Brazilian Foreign Minister Celso Amorim sought to play down the potential impact of such a move. As he stepped outside a meeting with other chancellors at Copacabana Palace hotel, Amorim said the Mercosur bloc was becoming increasingly important for the world and essential for its member countries. "The truth is that the Mercosur is ever stronger, and increasingly important for the world. Mercosur is essential for all countries, let's be clear," he said. Kirchner arrived ahead of most presidents, but did not speak to the press as he stepped in the Copacabana Palace. Mercosur counts Brazil, Argentina, Uruguay, Paraguay and Venezuela as full members. Bolivia and Chile are associate members.