From left: Luiz Inacio Lula da Silva, Hugo Chavez, Nestor Kirchner and Evo Morales

An emergency summit of four South American countries has apparently defused a regional crisis over Bolivia's decision to nationalize its oil and natural gas industries.

The presidents of Argentina, Brazil and Venezuela met with Bolivian counterpart Evo Morales Thursday in the northern Argentine town of Puerto Iguazu. After the meeting, the leaders issued a statement affirming Bolivia's "sovereign right" to control its natural resources.

They also agreed to enter into a series of bilateral talks with La Paz to negotiate gas prices and foreign production.

All four presidents dismissed talk of a rift between the two more radical leaders and the two moderate leftists of the South American countries. Mr. Morales and Venezuela's Hugo Chavez take a stronger socialist position than Argentina's Nestor Kirchner and Luiz Inacio Lula da Silva of Brazil.

Mr. Morales nationalized his country's energy industry Monday, posting troops at Bolivia's gas fields.

Foreign energy companies will now have to sign new operating contracts within 180 days, or leave Bolivia and turn over most production control to its state-owned energy company.

Brazil and Argentina rely heavily on Bolivian gas. Brazil's state-owned oil company, Petrobras, said it would suspend investments in Bolivia in response to the nationalization.