The US intelligence agencies are facing fresh embarrassment after WikiLeakspublished what it described as the biggest-ever leak of confidential documents from the CIA detailing the tools it uses to break into phones, communication apps and other electronic devices.

The documents focus mainly on techniques for hacking, including how the CIAcooperated with British intelligence to engineer a way to compromise smart televisions and turn them into improvised surveillance devices.

The leak, dubbed “Vault 7” by WikiLeaks, will once again raise questions about the inability of US spy agencies to protect secret documents in the digital age. It follows disclosures about Afghanistan and Iraq by Chelsea Manning in 2010 and about the National Security Agency and Britain’s GCHQ by Edward Snowden in 2013.

According to the documents:

CIA hackers targeted smartphones and computers.

The US consulate in Frankfurt, the biggest in the world, is home to a “sensitive compartmentalised information facility” that used digital specialists from the CIA and other US intelligence agencies.

A programme called Weeping Angel describes how to attack a Samsung F800 TV set so that it appears to be off but can still be used for monitoring.

Jonathan Liu, a spokesman for the CIA, declined to confirm whether the leaked documents were accurate, even though WikiLeaks has a long track record of publishing authentic material. “We do not comment on the authenticity or content of purported intelligence documents,” Liu said.

But it is understood the documents are genuine and a hunt is under way for the leaker. The leaks come at an especially sensitive juncture, with the US intelligence agencies involved in confrontation with the president, Donald Trump, over alleged Russian hacking to influence the US election.

The latest revelations will renew suspicion that Russia is again responsible and increase fears that it might choose to interfere in upcoming French and German elections.

Julian Assange, the WikiLeaks editor-in-chief, said the disclosures were “exceptional from a political, legal and forensic perspective”.

WikiLeaks shared the information in advance with Der Spiegel in Germany and La Repubblica in Italy.