(Lobby of the CIA Headquarters Building in Langley, Virginia.Thomson Reuters)

The Central Intelligence Agency has launched a manhunt for a traitor within its ranks after what has been called one of the worst security breaches in the organization's history, CBS News reported on Wednesday.

A joint CIA-FBI investigation is underway to determine how WikiLeaks got hold of thousands of top-secret files and published them in March — allegedly by way of a CIA employee or contractor who operated a tool normally used by the spy agency to infiltrate various electronic devices, from smartphones to smart televisions and computers.

The breach has been referred to as "Vault 7" by WikiLeaks.

The CIA did not say publicly how or when the information was stolen. But it said that the insider had physical access to the files and that most of the files were stored in a "highly secure section" of the agency, CBS reported.

Experts say the files appear to be genuine, but the CIA did not comment on their authenticity. CIA spokeswoman Heather Fritz Horniak delivered a stern rebuke against WikiLeaks.

"The American public should be deeply troubled by any WikiLeaks disclosure designed to damage the intelligence community’s ability to protect America against terrorists and other adversaries," Horniak said. "Such disclosures not only jeopardize US personnel and operations, but also equip our adversaries with tools and information to do us harm.

"This is the kind of disclosure that undermines our country, our security, and our well-being," White House press secretary Sean Spicer said earlier in March. He declined to comment on the authenticity of the leaked documents.

(CIA director Mike Pompeo.Joe Raedle/Getty Images)

Speaking at the Center for Strategic and International Studies in Washington on April 13 in his first public speech as head of the CIA , director Mike Pompeo slammed WikiLeaks for playing a role in the dissemination of the files.

"It is time to call out WikiLeaks for what it really is: a nonstate hostile intelligence service often abetted by state actors like Russia," he said, referring to the organization's possible ties to the Kremlin.

Pompeo continued to rail against WikiLeaks and its founder, Julian Assange, asserting that the Russian military "had used WikiLeaks" to release emails and documents damaging to the US Democratic Party — believed to be part of a larger bid by Russia to influence the 2016 presidential election.

Pompeo added that Russia Today, a state-sponsored media network that has offices in the US, was "Russia's primary propaganda outlet," and that it "has actively collaborated with WikiLeaks," according to The Wall Street Journal.