As dignitaries from three continents looked on, the foreign ministers of the two South American nations signed the accord in Brazil's capital, where most of the peace talks took place.

The treaty sets the boundary on a contested 78 km section of their border in the Andean foothills. Both laid claim to the jungle-cloaked area that was left undefined in the 1942 Rio de Janeiro protocol that set territorial limits.

Presidents Alberto Fujimori of Peru and Jamil Mahuad of Ecuador looked on from a dais, sitting on either side of Brazilian President Fernando Henrique Cardoso.

They were accompanied by Presidents Eduardo Frei of Chile, Carlos Menem of Argentina, Hugo Banzer of Bolivia and Andres Pastrana of Colombia. King Juan Carlos and Queen Sofia of Spain also attended, while the United States was represented by US envoy Luigi Einaudi andThomas `Mack' McLarty, a former aide to US President Bill Clinton.

``It's been a good week for peace accords, with Ireland and Israel and now this,'' said McLarty. ``Hopefully, Kosovo will move forward in the near term.''