Lawyers for Sean Combs, the hip-hop mogul who is battling federal racketeering and sex trafficking charges, accused the government on Wednesday of leaking hotel surveillance footage of him brutally beating his former girlfriend to CNN, saying that they may ask for the widely published video to be barred from his trial.

Prosecutors have made clear in court papers that the video — which shows Mr. Combs assaulting the singer Cassie in a hotel hallway in 2016 — is a key piece of evidence in their case. The surveillance footage was published by CNN in May, prompting Mr. Combs to apologize publicly for “inexcusable” behavior.

It has never been clear how the footage made its way to the news organization, but in the court filing on Wednesday, lawyers for Mr. Combs, who has pleaded not guilty and has vehemently denied the criminal charges, accused the Department of Homeland Security, which executed raids of the defendant’s homes in March, of being responsible for the leak.

“The videotape was leaked to CNN for one reason alone: to mortally wound the reputation and the prospect of Sean Combs successfully defending himself against these allegations,” the lawyers, Marc Agnifilo and Teny Geragos, wrote.

The court filing cited a federal rule of criminal procedure that prohibits prosecutors or government agents from disclosing matters occurring before a grand jury. The defense accused Homeland Security officials of a series of leaks, including in anonymous comments to The New York Post, that they said “all but ensured” that the grand jury and a potential trial jury would be tainted. The lawyers asked for a hearing to determine the government’s culpability in the leaks.

A spokesman for the U.S. attorney’s office for the Southern District of New York, which is overseeing the prosecution, declined to comment. Representatives for the Department of Homeland Security and CNN did not immediately respond to requests for comment.