Instagram has blocked searches for certain terms associated with the suspected illegal sale of drugs via its service.
The photo-themed social network took the measure after being asked to respond to an investigation by #BBCtrending—a new social media series.
The journalists had uncovered many pictures and videos of narcotics posted alongside text advertising their sale.
Instagram is owned by Facebook.
The firm has a policy of acting on posts reported as being inappropriate, but it believes it would be impractical and invasive to search for such material.