Kelly Clarkson Says Strange Man’s Showing Up at Her Home, Files Police Report

Kelly Clarkson says a strange man is showing up to her house, trespassing on her property and leaving her unwanted gifts … so, now she’s getting the police involved.

Law enforcement sources tell TMZ … for the past month, the same man’s been popping up at Kelly’s L.A. area home, going up to her porch and dropping things off for her.

We’re told the guy’s leaving behind cards, plants and other random items for Kelly … even though she told cops she’s never met him before, and doesn’t know who he is.

Our sources say Kelly has yet to come face-to-face with the intruder, but we’re told her security was concerned enough to call LAPD to file a report … and now LAPD Threat Management is investigating.

Cops see the man’s alleged behavior as very troubling — they don’t know yet if it’s a fan who means no harm, or a situation that could escalate into something far more sinister.

Our sources say Kelly’s got surveillance footage of the guy dropping stuff off on her porch … and LAPD is trying to identify him for a background check, and to assess potential threats.