Paris Hilton getting on dirty with her sister (Pics inside)

Sex-mad Paris is well-known for her lack of inhibitions.

But even she was pushing back the boundaries when she posed for this sizzling set of snaps on a visit to the Playboy Mansion in LA.

Paris, wearing stockings and suspenders and an animal-print basque, seems to be loving every minute of being captured bottom to bottom with Nicky, 23.

Their feet are clamped on the roof of their limo as they soak up the limelight.

In another shot Paris, 25, hugs and kisses her wide-eyed little sis - who is dressed in only a silky slip.

Our snapper said: “I know sisters can be a touchy feely but this was taking it to an extreme.