Shocking new claim from Diddy and his legal team ... they believe the federal government "orchestrated" the leak of the Cassie beating video to the media.

According to new legal docs, obtained by TMZ, Diddy's attorneys accuse the feds of misconduct in his criminal case ... namely, by allegedly orchestrating the leak of the Cassie tape to CNN.

The video in question is from 2016 and it shows Diddy brutally beating Cassie in the hallway of a swanky Los Angeles hotel during their relationship.

In the docs, Diddy is specifically blaming the Department of Homeland Security ... not the U.S. Attorney's office.

Diddy's lawyers claim the day CNN published the Cassie video -- May 17 -- a correspondent from the network contacted a member of Diddy's team to seek comment on a video they intended to publish in a few hours ... with the correspondent indicating CNN came "across a video and currently have in our possession surveillance footage from the Intercontinental Hotel in Los Angels in 2016."

His attorneys say after being approached by CNN, they emailed the prosecutors assigned to Diddy's case and told them they had gotten word CNN had been given a video tape of the Intercontinental Hotel from 2016 and told prosecutors, "My concern is that someone (not any of you and not the lead case agents) provided this footage to CNN. I bring this to your attention solely because I imagine you didn't want this to happen any more than I do."

Diddy's lawyers say after CNN released the video on May 17, an Assistant United States Attorney assigned to the case responded, "We really appreciate you giving us a heads up. We have now seen the video."

His attorneys say DHS is likely the source of the leak for a few reasons ... pointing out DHS agents were often quoted in news stories about the Diddy raids and investigation.

Diddy's legal team also says Cassie was likely not a source of the leak because her lawsuit against Diddy didn't make it seem like she had the tape and she had no motive to leak it to the press.

Instead, Diddy's camp says the tape being leaked to CNN "shows a motive to damage Mr. Combs' reputation without remuneration—a motive held by federal agents."

The timing of the leak is also interesting, Diddy's lawyers say ... pointing out on May 17 there was a break in the Donald Trump trial, and thus a slow news day that would give more attention to the Cassie tape.

Diddy's lawyers want an evidentiary hearing to craft a remedy so the judge can assess and determine appropriate relief.