Prosecutors Deny Leaking Diddy Assault Video, Didn't Have Clip at Time

The assault video showing Diddy beating his then-girlfriend Cassie Ventura wasn't released by the feds, they claim ... saying CNN got it from someone else -- and, Diddy's arguments claiming otherwise are straight-up false.

Prosecutors filed a motion in U.S. District Court in opposition to a motion Diddy filed earlier this month alleging he believed the government gave the video to the popular cable news channel back in May ... and, they basically say this can't be true 'cause they didn't even have it yet.

According to prosecutors, federal agents had searched for the video early in the investigation, but it had mysteriously disappeared from the hotel's server ... and didn't crop up again until CNN released the footage on May 17.

Prosecutors say they ultimately downloaded the video from CNN's site ... but, they are still not in possession of the original.

As we reported ... in a previous filing, Diddy's team blames unnamed agents in the Department of Homeland Security ... who they say are a likely source of the leaks -- pointing out DHS agents are often quoted in news stories about Diddy's case.

Federal prosecutors point out way more people than federal agents had access to the tape ... with hotel employees, the security team contracted at the hotel, and even members of Diddy's staff could have leaked the video instead.

The feds insist there's no need for an evidentiary hearing into whether prosecutors leaked the clip.

Diddy's still locked up in federal detention in Brooklyn while awaiting the trial in his criminal case. He faces charges of racketeering conspiracy, sex trafficking by force, fraud or coercion, and transportation to engage in prostitution. He's also dealing with dozens of civil suits.