Brazil and Mexico have both demanded an explanation from the US over claims that the National Security Agency (NSA) spied on their presidents.

Internet data from Brazilian leader Dilma Rousseff and Mexico's Enrique Pena Nieto was intercepted, journalist Glenn Greenwald told Brazil's TV Globo.

Mr Greenwald obtained secret files from US whistle-blower Edward Snowden.

Julia Carneiro reports from Rio de Janeiro.