Venezuela’s deputy foreign minister for North America and Europe, Alejandro Fleming, delivered a letter to the U.S. charge d’affaires in Caracas, Lee Mclenny, on Thursday to complain about the espionage conducted by the National Security Agency against the Venezuelan state-owned oil company PDVSA.

Venezuelan President Nicolas Maduro’s government is responding to a joint report by teleSUR and The Intercept that cites a leaked classified NSA document that shows that the spy agency spied on top PDVSA officials as part of an operation carried out with the U.S. Embassy in Caracas.

President Maduro denounced the U.S. spying and said in response that he would revise bilateral relations with Washington.

The two media organizations uncovered how the NSA accessed the internal communications of Venezuela's state oil company and acquired sensitive data that it planned to exploit in order to spy on the company’s top officials.

The highly classified NSA document leaked by NSA whistleblower Edward Snowden also showed that the CIA was operating out of the U.S. Embassy.