Mr O'Brien and his wife Anne-Marie were among a number of observers who attended today's second day of an An Bord Pleanála oral hearing into the Tipperary Venue.
Businessman Richard Quirke wants to develop an 800-acre site at Two Mile Borris, outside Thurles, into a complex which would include a hotel and casino, golf course, indoor entertainment venue, equestrian centre and horseracing and greyhound racing tracks.
A number of local residents, along with An Taisce, have objected to the plan on the grounds of its size, sustainability and impact on the surrounding landscape and road network.
Horseracing Ireland, Bord na gCon, Horse Sport Ireland, Shannon Development and the Thurles Chamber of Commerce are among the bodies who have made submissions in favour of the project.
Speaking from her statement on behalf of her husband and herself, Anne-Marie O'Brien said the plans had their 'full support' and that the Tipperary Venue would be 'an incredible asset' to the whole horseracing and equestrian industry in Ireland.
