Justin Bieber Sued Over Alleged Subway Beatdown

Justin Bieber has just been sued by a photog who claims Bieber's bodyguard locked him in a Subway restaurant and then injured him the night the singer was busted for DUI.

Manuel Munoz claims in a new lawsuit -- obtained by TMZ -- he was taking pics of Justin as the singer was leaving SET Nightclub in Miami Beach last January ... just minutes before he was popped by cops.

Munoz says Justin's bodyguard was upset about the photos and chased him into a nearby Subway.  Munoz says the bodyguard locked the restaurant door and cornered him in the bathroom, demanding that he delete the photos. 

Munoz says the bodyguard tried to forcibly remove the memory card and then kicked and punched him.  He says the camera was damaged.

Check out Munoz' 911 call ... he says the bodyguard eventually got the memory card.

We got hold of a police report Munoz filed ... and there is a problem.  Munoz never says he was punched or kicked.  It says the bodyguard tripped him, causing him to sustain a "small scratch in his left knee."

The police report also says the 2 haggled in the restroom ... Munoz telling the bodyguard he'd give Bieber the pics for $10K  but the bodyguard drew the line at $5K.

Munoz is suing Bieber and bodyguard Dwayne Patterson for unspecified damages.

Bieber's rep tells TMZ, "This new lawsuit filed by a paparazzo is yet another shakedown for money ... The paparazzo admits that Justin was not present at the alleged 'assault.' ... The paparazzo told the police he had only scratched his knee when he was allegedly tripped, but now claims he was beat up ... There are no damages."