CNN Destroys Video of Diddy Beating Cassie, Diddy's Lawyers Claim

5:45 PM PT -- "CNN never altered the video and did not destroy the original copy of the footage, which was retained by the source. CNN aired the story about the video several months before Combs was arrested."

5:40 PM PT -- Diddy's legal team tells TMZ ... "Our written and oral communications with CNN’s counsel were clear - they destroyed the original video file they received from their source."

Bombshell in the Diddy prosecution ... CNN destroyed the only known copy of the 2016 video in which Diddy is seen beating Cassie in the hallway of an L.A. hotel ... this according to new court documents.

Diddy's defense team and prosecutors filed a joint letter about evidence in the case. According to the defense ... CNN purchased the video showing Diddy attacking Cassie in the hallway of the InterContinental Hotel in L.A. The letter claims "CNN purchased the only known copy of the Hotel's surveillance footage, uploaded that footage into a free editing software, altered the video and then destroyed the original footage, even though it knew about and repeatedly reported about the federal investigation."

The defense claims CNN altered and edited the footage by "covering the time stamp and then changing the video sequence. It also includes speeding up the video to make it falsely appear that the actions in the video are taking place faster than they are. As a result, the CNN videos do not fairly and accurately depict the events in question."

The InterContinental Hotel has closed down in that location and we're told no other video of the incident exists.

It seems inevitable ... the defense will try and exclude the video from Diddy's upcoming trial. Diddy is not being prosecuted for the beating -- that's a state matter and the statute of limitations has run -- but prosecutors want to use it to show Diddy's alleged violent propensities.

The reality is this ... courts almost never admit video evidence where the video is edited -- judges insist on the raw footage, so there's an extremely good chance this video will never be played to a jury.