Both Brazil and Mexico summoned the respective United States Ambassadors after the latest revelations from journalist Glenn Greenwald that the US National Security Agency (NSA) had spied on their countries' presidents.

Mexico says the allegations, based on intelligence smuggled out of the US by fugitive leaker Edward Snowden, would be a serious violation of its sovereignty if proven true, and is asking the United States to investigate.

Brazil's government is giving the United States until the end of the week to provide a written explanation; Brasilia was already seriously annoyed by earlier reports of the NSA allegedly spying on the emails and phone calls of Brazilians and its lawmakers. 

The report throws a spanner in the plans of the US, which wants to sell 36 F-18 fighter jets to Brazil.  But a source inside the Brazilian government says the espionage allegations have dealt a setback to that US$4 billion deal.  President Dilma Rousseff was also scheduled to visit President Obama in Washington later this year.  For the moment, that visit is still on.