Bord Pleanála started an oral hearing into the proposed Tipperary Venue planned for the site in Two-Mile-Borris near Thurles.
Opponents of the project told the hearing it could impact negatively on Irish horseracing but backers say the leisure venue will create up to 900 jobs during construction as well as 1,350 full-time jobs when complete.
As well as the hotel and casino development, the project includes horse and greyhound racing tracks, a 15,000-capacity indoor entertainment arena, golf course, replica of the White House, and international equestrian centre.
Supporters are expected to enter submissions to the hearing including representatives from Horseracing Ireland, stud giant Coolmore, training establishment Ballydoyle, Horse Sport Ireland, greyhound body Bord na gCon, Shannon Development and Thurles Chamber of Commerce.
The complex is the brainchild of businessman and former garda Richard Quirke, the man behind the Dr Quirkey’s Goodtime Emporium amusement arcade on Dublin’s O’Connell Street. Its main political supporter is Michael Lowry, the independent TD for North Tipperary, who is expected to make a submission during this week’s hearing.
North Tipperary County Council granted planning permission to the Tipperary Venue last year but local residents and An Taisce subsequently lodged appeals.
Sustainable planning expert and barrister James Nix said yesterday the "racino" complex would spell the end of racing at the current Thurles and Tipperary (Limerick Junction) courses as well as a "diminution" in racing fixtures elsewhere.