Kathy Griffin's neighbor says the comedian is more than a snoop ... she's a spy.

Jeffrey Mezger just filed legal docs, obtained by TMZ, that say he and his wife were told by LAPD Kathy and her boyfriend have been using both video and audio electronic devices to eavesdrop on conversations in his backyard, including his patio and Jacuzzi area.

Various conversations were captured, including talks between him and his grandchildren.

Mezger says it's an invasion of privacy.

Mezger and Kathy are locked in a Hatfield/McCoy type neighborhood war. They've filed mutual restraining orders against each other.

The feud erupted when Kathy and her boyfriend began complaining about noise coming from Mezger's property. He says he's been in the neighborhood since 1999 and no other neighbor has griped.

Griffin admits she has security cameras on her property for protection, but is adamant there is nothing illegal about her recording. She claims the cameras can only pick up sounds on her property ... so there is absolutely no eavesdropping.