Diddy was face-to-face with federal agents Monday as they intercepted his plane ... and TMZ now has a photo showing the interaction ... this as his associate was taken into custody.

Check out the pic showing the rap mogul wearing a white T-shirt and blue pants as law enforcement surrounds him and the rest of his entourage.

Diddy's got his back to the camera and doesn't appear to have been detained. You also see 25-year-old Brendan Paul in the mix ... who was later arrested and booked on drug charges following a search.

As we reported, cops say they found cocaine and weed in Paul's travel bag. He was booked and later released.

We obtained another pic that shows the same gaggle of people on the tarmac. You don't see Diddy in this particular shot -- much like the other photo we got of this exact scene, only from a different angle -- but BP is right there once again, in an unmistakable blue sweater.

Diddy showed up later this same day ... pacing around the airport, restless in the aftermath.

As we reported ... Paul was name-dropped in Rodney Jones' explosive lawsuit against Diddy -- which alleges the young man worked as a "mule" for his former boss, dealing in drugs and firearms. The suit includes photos of Paul hanging out with Diddy.

Diddy has denied all of Rodney's claims.

Worth noting ... Diddy hasn't been arrested or charged at this point, but as you know, the feds raided his homes in L.A. and Miami in search of incriminating evidence. The homes were turned upside down, with documents strewn about and other items dumped on floors.