Sources with direct knowledge tell TMZ ... the grand jury is absolutely still convened, and this week it heard testimony from a male escort who said he's interacted with Diddy in the past.

We're told the testimony covered Diddy's alleged outreach to the escort and his willingness to participate in a "Freak Off."

Our sources say the grand jury testimony also focused on travel ... including whether Diddy had ever transported the escort across state lines or into another country.

They also asked about alleged payments made to the escort ... specifically whether any such payments were made in cash or via wire transfer.

We've heard from multiple sources ... the reason the grand jury is still meeting is because prosecutors might seek to bring additional charges in a superseding indictment against Diddy.

Now, a source close to Diddy tells us, “He’s focused on the facts and preparing his defense. He maintains his innocence of these charges.”

Sex workers have apparently piqued the feds' interest in recent days. As we told you, a different male sex worker spoke to federal investigators earlier this week ... detailing an alleged sexual encounter with Diddy and another woman -- and, handing over an alleged sex tape to feds.

We knew U.S. Attorney Damian Williams was still looking into Diddy's case to potentially add charges. Remember, when announcing the indictment against Diddy, Williams was asked if more charges could be brought related to the case ... and, he "wasn't taking anything off the table."

As you know, Diddy's already pled not guilty to sex trafficking, kidnapping and racketeering charges ... and, he's currently being held without bail in a notorious NYC jail.

We get into all of this and more in our new documentary "The Downfall of Diddy: The Indictment" streaming now on Tubi.