Obama had made the pledge to "continue to work" with the two governments during separate bilateral meetings with Brazil's Dilma Rousseff and Mexico's Enrique Pena Nieto at the G20 summit on Thursday, said Ben Rhodes, Obama's deputy national security advisor for strategic communications.

The governments of both Latin American nations have demanded explanations from the United States over reports that the National Security Agency snooped on communications of Rousseff and Pena Nieto.

In an escalation of the row, Brazil halted preparations for a Washington trip by Rousseff, while Mexico demanded an investigation into the claims.

Rousseff and Pena Nieto's meetings with Obama at the G20 summit in Saint Petersburg came four days after the report by US journalist Glenn Greenwald, who has access to documents leaked by fugitive former NSA contractor Edward Snowden.