The photos have surfaced on several websites … showing Heidi on vacation in the south of France with her bodyguard boyfriend … sans bikini top. 

There’s just one problem … it’s unclear which French magazine published the original pics. 

Sources close to Heidi tell TMZ … the supermodel’s camp is on the hunt for the source publication … claiming her right to privacy was violated because she was on a private and secluded beach at the time the pics were taken.  

Sound familiar? We’re told Heidi is comparing her situation to that of Kate Middleton … who also believes she was the victim of privacy invasion when a paparazzo snapped topless pics of her while she was sunbathing at a private chateau in France. 

We’re told … just like Kate, Heidi wants to sue someone’s ass … but realizes she might have better luck if she waits for Kate to blaze the legal trail.  

Long story short — if Kate’s legal attack is successful, Klum can simply copy her playbook … and if it’s not, she can learn from Kate’s mistakes.

Supermodels — they’re not as dumb as you think.