A top One Nation figure touted as a future leader of the party in its Queensland heartland is being investigated by police over assault allegations.

Sean Black, media and policy adviser to outspoken One Nation senator Malcolm Roberts, is the subject of a complaint of alleged assault lodged with Queensland Police in August, Fairfax Media can reveal.

Senator Malcolm Roberts and adviser Sean Black. Credit:Andrew Meares

"Queensland Police received a complaint in relation to this matter," a police spokesman said. "At this stage no one has been charged.

"Investigations into the complaint are continuing."