Feds Say Diddy's 55th Birthday Celebration Was a Ruse to Influence Jury

Diddy is getting creative behind bars to sway a potential jury in his favor -- and he's even used his recent birthday celebration to obstruct justice in his federal criminal case, prosecutors say.

According to new legal docs, obtained by TMZ ... federal prosecutors say Diddy -- who is currently behind bars -- recruited family members to plot and execute a media campaign around his 55th birthday earlier this month for the purpose of influencing a jury at trial.

--You may recall ... Diddy's 7 kids posted a gushing Instagram video tribute to the music mogul and they let baby Love take center stage in the singing of "Happy Birthday." The children also wrote in the caption, "Happy Birthday Pops, we love you! 🎂❤️."

But, the feds say it was all staged to win over potential jurors ... saying the IG video -- at Diddy's "carefully curated direction" -- was posted by his kids to each of their social media accounts.

Prosecutors say Diddy monitored audience engagement from within the Metropolitan Detention Center in Brooklyn -- and specifically discussed with his family the video having its "desired effect on potential jury members in this case."

The feds also laid out several other reasons why Diddy should stay locked up at MDC as he awaits trial on charges of racketeering, sex trafficking and transportation to engage in prostitution.

Prosecutors say Diddy is a flight risk because of his unlimited resources, a danger to the public due to his alleged history of violence and his neverending efforts to contact possible witnesses and abuse victims who could provide critical testimony against him.

As we reported ... Diddy is trying once again to get released on a $50 million bond after being denied by judges 2 times before. We'll have to wait and see if the third time's the charm.