A top U.S. beauty pageant queen has handed back her crown after a pornographic video allegedly featuring her appeared online.

Miss Delaware Teen Usa Melissa King, 18, insists the girl in the hardcore sex footage is not her, but she has still handed in her resignation to pageant bosses.

The video was shot last summer (12), according to Tmz.com. King was crowned Miss Delaware Teen Usa in November (12).

Pageant runner-up Hailey Lawler is expected to be named her replacement in the coming days.