The BBC understands that Nicolae Nicola - a prominent member of the Roma community in Northern Ireland - has been arrested and questioned by police.
The PSNI told the Nolan Show "officers in Belfast, investigating the contents of a number of social media posts and posters which were erected in public areas in south Belfast in August, arrested a 29-year-old man".
The man was arrested last Friday.
He was later released on police bail, pending further enquiries.
Mr Nicola has been the public face of the Romanian Roma Community Association of Northern Ireland (RRCANI).
This is the third arrest to arise out of a PSNI investigation into alleged exploitation and criminality affecting the Roma community.
A 31-year-old man was arrested last December and a 40-year-old man in October.
Both were released on police bail.