South American leaders sought to avert a regional crisis over Bolivia's nationalization of its natural-gas industry as Venezuelan President Hugo Chavez flew with Bolivian President Evo Morales to a hastily arranged summit in northern Argentina on Thursday. Morales announced Monday that he had nationalized Bolivia's natural-gas reserves and will reduce foreign participants to minority shareholders, giving the companies six months to renegotiate contracts or leave Bolivia. Chavez, a socialist and political mentor of the leftist Morales, said he came to Bolivia late Wednesday not to give advice but to offer “congratulations and learn from Bolivia's wisdom.” “With good will, Morales will reach the agreements he needs to make with the foreign companies,” Chavez said after arriving in La Paz. Chavez spoke after Brazil, Bolivia's biggest gas client, announced it would cut off all new petroleum investment in Bolivia, where it has invested $1.6 billion to increase production over the last decade. Morales and Chavez flew to the Argentine city of Puerto Iguazu along the border with Brazil to join Brazilian President Luiz Inacio Lula da Silva and Argentine President Nestor Kirchner. While Lula said he believes he can negotiate a solution to the controversy, he asserted that he will defend contracts giving Brazil rights to Bolivian gas. “The fact that Bolivia has rights does not deny the fact that Brazil has rights in the matter as well,” he said. Morales and Chavez also plan to discuss Chavez's idea to construct a 9,000-kilometer pipeline linking Venezuela's vast natural-gas reserves through Brazil to Argentina, Chavez said. The pipeline, estimated to cost $25 billion, would also branch to Bolivia, Paraguay, and Uruguay, though experts have said it could cost more and environmentalists say the plan could damage the Amazon rain forest.