FBI Director Kash Patel found a trove of sensitive documents related to the origins of the Trump–Russia probe buried in multiple "burn bags" in a secret room inside the bureau, sources told Fox News Digital, Fox News reports.

Sources said that multiple burn bags were found and filled with thousands of documents.

Sources said that the "burn bag" system is used to destroy documents designated as classified or higher.

The bags were allegedly found in a “secret room.” This is the so-called Sensitive Compartmented Information Facility (SCIF). Fox News sources reported that Patel and his team discovered a previously unknown SCIF in the FBI building.

Patel, in a June interview with podcast host Joe Rogan, revealed that he found a room full of documents and computer hard drives "that no one had ever seen or heard of."

Sources said that one of the documents FBI officials found in a burn bag was the classified annex to former special counsel John Durham's final report, which includes the underlying intelligence he reviewed.

Sources exclusively briefed Fox News Digital on some of the contents of the classified annex—including that the US intelligence community had credible foreign sources indicating that the FBI would play a role in spreading the alleged Trump–Russia collusion narrative.

The declassified annex will be transmitted to Senate Judiciary Committee Chairman Chuck Grassley, who ultimately will release the document to the public.

"Ultimately, the release of the classified annex will lend more credibility to the assertion that there was a coordinated plan inside the U.S. government to help the [Hillary] Clinton campaign stir up controversy [before the 2016 US presidential election] connecting Trump to Russia," the source, who was granted anonymity to discuss sensitive intelligence matters that have not yet been made public, told Fox News Digital.