VENEZUELA has demanded that the US identify the agents who spied on national oil firm PDVSA.

Deputy Foreign Minister Alejandro Fleming delivered a formal letter of protest to charge d’affaires Lee McClenny, the top diplomat at the US embassy, in Caracas on Thursday.

Wednesday’s revelations by US National Security Agency (NSA) whistleblower Edward Snowden that spies had intercepted emails from Petroleos de Venezuela SA (PDVSA) prompted Caracas to review its already strained relations with Washington.

“Venezuela requires … the identity of the agents involved in this unprecedented, unacceptable act,” said the Foreign Ministry in a statement.

While he did not deny the reports on Thursday, US State Department spokesman John Kirby claimed that such spying was not intended to benefit US business interests.

“There’s no intent to use electronic surveillance to benefit commercial gains. That’s not changed,” he told reporters in Washington.

Mr Kirby also claimed that the US had “no interest or intent to destabilise the Venezuelan government.

“We’ve seen many times that the Venezuelan government tries to distract from its own actions by blaming the US and other countries for events inside its own country.”

US-funded opposition forces tried to violently overthrow Venezuela’s democratically-elected government in 2002 — followed by a three-month lock-out by PDVSA managers — and again last year.

Parliamentary elections in Venezuela are set for December 6.