Brad Pitt's new movie set got raided by heavily armed police officers...

Hungarian police raided the set of Brad Pitt's new movie today -- confiscating a massive stash of high-powered guns ... including AK-47s and sniper rifles ... filled with live ammo.

According to Hungarian authorities, the guns -- which were to be used as props in Brad's new zombie flick "World War Z" -- hadn't been properly disabled, and some even contained live rounds.

Authorities seized 85 weapons in total from a warehouse in Budapest -- and called the entire situation "a disaster waiting to happen." Brad was not present during the raid.

A publicist for the film claims ... "We are working with the authorities to resolve the matter and have no further comment at this time."