The FBI is launching a hunt to unmask the source of the CIA document leak which has rocked the US intelligence services.

Thousands of documents were suddenly published by anti-secrecy group WikiLeaks yesterday, purportedly revealing hacking tools which the CIA uses to break into devices such as phones, computers and smart TVs.

It the latest in an embarrassing series of revelations, and WikiLeaks has promised more to come.

Investigators are now carrying out a massive operation to find who released the documents, with the source likely to face a long jail term if caught. The most recent whistleblower to be convicted under the Espionage Act, Chelsea Manning, was given a 35 year sentence, although this was commuted in the final days of Barack Obama's presidency.

Scroll down for video

The documents purportedly shed light on hacking tools used by the CIA

Yesterday a huge number of documents were released purportedly revealing the hack tools the CIA uses to break into phones, computers and even smart TVs

WikiLeaks claimed the latest haul, which it dubbed 'Vault 7, Year Zero', exposed the agency’s entire hacking tool kit.

It said this constituted an even bigger and more significant breach of US intelligence than the National Security Agency files leaked by analyst Edward Snowden.

Snowden, who fled to Russia in 2013 after the Justice Department announced two charges of breaching the Espionage Act of 1917, tweeted yesterday that the latest trove of files is a 'genuinely a big deal'.

Whisteblower Edward Snowden responded to the leak, which he described as 'genuinely a big deal'

Former CIA Director Mike Hayden told MSNBC he had undertaken only a cursory review of the documents, but that if they were what they were purported to be, it would amount to a 'very extensive file of the tactics, techniques, procedures, targets and other political rules' under which the CIA hacks targets.

'If it is that, it would be very, very damaging,' he said.

The CIA has refused to be drawn on whether the documents are genuine, with spokesman Jonathan Liu stating: 'We do not comment on the authenticity or content of purported intelligence documents.'

White House spokesman Sean Spicer also declined to comment.

White House spokesman Sean Spicer yesterday declined to comment on the release of thousands of documents by WikiLeaks

WikiLeaks itself has been vague about where the information came from. In a statement it said the material came from 'an isolated, high-security network' within the CIA's Center for Cyber Intelligence.

But it has not revealed whether the files were removed by a rogue employee or whether the theft involved hacking a federal contractor working for the CIA or even breaking into a staging server where such information might have been temporarily stored.

A former intelligence official told the Washington Post there was going to be a 'major mole hunt', and added: 'If this is all correct, it’s a big deal.'

A statement from WikiLeaks said: 'This extraordinary collection, which amounts to more than several hundred million lines of code, gives its possessor the entire hacking capacity of the CIA.

'The archive appears to have been circulated among former U.S. government hackers and contractors in an unauthorized manner, one of whom has provided WikiLeaks with portions of the archive.'

Cases which shook the intelligence community: Manning, Snowden and Martin

The trove of documents released by WikiLeaks yesterday are the latest in a recent line of high-profile leaks.

Following data breaches by Chelsea Manning and Edward Snowden, Barack Obama set up the National Insider Threat Task Force to try and prevent intelligence insiders releasing damaging information.

Former intelligence analyst Manning, who declared as transgender after her 2013 Espionage Act conviction, leaked more than 700,000 classified documents.

Whistleblower: Chelsea Manning (left) formerly known as Bradley Manning (right) leaked more than 700,000 classified documents

Edward Snowden fled to Moscow in June 2013, having released thousands of documents revealing the widespread surveillance on ordinary Americans through the bulk collection of metadata

These included a video showing a US Apache helicopter opening fire on a group which included two Reuters journalists.

In the final days of his presidency, Barack Obama granted Manning clemency, stating: 'The notion that the average person who was thinking about disclosing vital, classified information would think that it goes unpunished, I don’t think would get that impression from the sentence that Chelsea Manning has served.'

Harold T. Martin III is accused of stealing documents about cyberweapons and is awaiting trial

Snowden fled to Moscow in June 2013, having released thousands of documents revealing the widespread surveillance on ordinary Americans through the bulk collection of metadata.

President Donald Trump has called the him a 'spy' and a 'traitor' who deserves to be executed.

Snowden was initially given three years' asylum in Russia in 2013 after fleeing the US, where he faced a maximum of 30 years in prison for leaking the NSA documents.

There is an ongoing probe into NSA contractor Harold T. Martin III, who is accused of taking home documents about US cyberweapons, which later appeared online.

The case against Martin has yet to be proved, and he denies breaching the Espionage Act. He was arrested by the FBI last year, and is awaiting trial.

President berates security services for series of leaks he brands a 'witch hunt'

During his election campaign, Donald Trump declared at a rally in Pennsylvania: 'I love WikiLeaks'.

But now he is in the White House, he has had a difficult relationship with intelligence services, and has berated insiders for a string of leaks, which he has branded a 'witch hunt'.

Last month national security adviser Michael Flynn was forced to quit after insiders revealed that he had secretly held meetings with Russia's ambassador, where sanctions against Putin's government were discussed.

Donald Trump has been a vocal critic of intelligence service employees who leak sensitive information to the public

Last month national security adviser Michael Flynn was forced to quite after insiders revealed that he had secretly held meetings with Russia's ambassador, where sanctions against Putin's government were discussed

Intelligence sources had claimed the Trump administration was told weeks before that Flynn was at risk of blackmail, and he failed to disclose the nature of his discussions.

On February 24, Trump voiced his ire on Twitter, writing : 'The FBI is totally unable to stop the national security "leakers" that have permeated our government for a long time. They can't even find the leakers within the FBI itself. Classified information is being given to media that could have a devastating effect on US. FIND NOW'.

At the start of this month, an intelligence source revealed to the Washington Post that Attorney General Jeff Sessions had twice met with Russian officials, but had not declared the meetings.

US President Donald Trump stands alongside US Attorney General Jeff Sessions, who intelligence service insiders revealed had met twice with Russian officials

The revelation prompted calls for his resignation, but Trump was defiant.

In another series of tweets the President wrote: 'Jeff Sessions is an honest man. He did not say anything wrong. He could have stated his response more accurately, but it was clearly not intentional.

'This whole narrative is a way of saving face for Democrats losing an election that everyone thought they were supposed to win. The Democrats are overplaying their hand.

'They lost the election, and now they have lost their grip on reality. The real story is all of the illegal leaks of classified and other information. It is a total "witch hunt"!'

Back in 1971, military analyst Daniel Ellsberg (pictured, front) released the now-infamous Pentagon Papers, published in the New York Times, which revealed that the Lyndon B. Johnson administration had systematically lied about involvement in Vietnam

A long history of whistleblowers within the intelligence services

Intelligence leaks are no new phenomenon, and the latest batch of documents follow in a long history of whistleblower releases.

In the past decade Manning and Snowden have taken their place among high-profile intelligence intelligence insiders who have spilled the beans on their employers.

Back in 1971, military analyst Daniel Ellsberg released the now-infamous Pentagon Papers, published in the New York Times, which revealed that the Lyndon B. Johnson administration had systematically lied about involvement in Vietnam.

Ellsberg faced spending the rest of his life behind bars, as he was charged under the Espionage Act, which carried a maximum sentence of 115 years.

However he walked free in May 1973 after Judge William Matthew Byrne Jr acquitted him following the revelation he had been the victim of illegal wiretapping.

Former FBI Associate Director Mark Felt (pictured, left, at a 1981 news conference) was revealed to be 'Deep Throat', the source who helped Washington Post reporters uncover the Watergate scandal

The year after the publication of the Pentagon Papers, the second most senior figure in the FBI turned whistleblower in a case that would stun the world.

FBI chemist Frederic Whitehurst went public with allegations of errors and misconduct in 1998

Mark Felt, the Bureau's Associate Director, helped Washington Post reporters Bob Woodward and Carl Bernstein uncover the Watergate Scandal, which led to the resignation of President Richard Nixon in 1974.

Branded 'Deep Throat' to keep his identity secret, he did not reveal his role in the scandal until 2005, three years before he died.

In 1998, FBI chemist Frederic Whitehurst went public with allegations of errors and misconduct in his department, prompting an overhaul of procedures.

He had joined the FBI in 1982 and was a Supervisory Special Agent in the FBI crime lab between 1986 and 1998.

The scientific misconduct he investigated and reported led to the FBI agreeing to 40 major reforms, including undergoing an accreditation process.

The CIA hacking tools revealed by WikiLeaks

WikiLeaks published thousands of documents yesterday described as secret files about CIA hacking tools the government employs to break into users' computers, mobile phones and even smart TVs from companies like Apple, Google, Microsoft and Samsung.

The documents describe clandestine methods for bypassing or defeating encryption, antivirus tools and other protective security features intended to keep the private information of citizens and corporations safe from prying eyes.

US government employees, including President Donald Trump, use many of the same products and internet services purportedly compromised by the tools.

The leak purportedly includes 8,761 documents and files from an isolated, high-security network situated inside the CIA's Center for Cyber Intelligence in Langley, Virgina (above)

The documents describe CIA efforts - cooperating with friendly foreign governments and the National Security Agency - to subvert the world's most popular technology platforms, including Apple's iPhones and iPads, Google's Android phones and the Microsoft Windows operating system for desktop computers and laptops.

The documents also include discussions about compromising some internet-connected televisions to turn them into listening posts.

One document discusses hacking vehicle systems, indicating the CIA's interest in hacking modern cars with sophisticated on-board computers.