Brisbane five-eighth Anthony Milford has been issued a concerning act notice by the NRL for kicking Jason Clark in the groin during the Broncos' 24-20 defeat of South Sydney on Thursday night.

The official warning from head office came after NRL officials reviewed footage which shows Milford's boot connect with Clark midway through the second half at ANZ Stadium.

In his follow-through from a clearing punt downfield, Milford appears to extend his kicking motion in the follow through with his right leg as the veteran forward moved up in defence.

Milford's unwanted contact to Clark's groin came as the Rabbitohs prop braced himself for a collision after applying kick pressure, warranting the concerning act notice for unnecessary contact.

Clark played out the rest of the game after recovering from the eye-watering blow, while the review panel found no other charges from the match.