The 29-year-old forward sat out training on Tuesday, June 6 in FAI National Training Centre as a precaution to nurse a knee injury, but he has now left camp.
Ireland will be back in training on Wednesday, June 7 at what will be an open session for supporters at the Aviva Stadium.
Supporters interested in attending the 11:00 session should access the stadium via Lansdowne Lane and through the Podium entrance.
Republic of Ireland squad
Goalkeepers: Darren Randolph, Keiren Westwood, Colin Doyle
Defenders: Cyrus Christie, Alex Pearce, Richard Keogh, Shane Duffy, John O'Shea, Kevin Long, Andy Boyle, John Egan, Stephen Ward
Midfielders: Aiden McGeady, Eunan O'Kane, Glenn Whelan, Harry Arter, Conor Hourihane, Alan Browne, Robbie Brady, Jeff Hendrick, Daryl Horgan, Wes Hoolahan, Callum O'Dowda, James McClean, Jonny Hayes
Forwards: Jonathan Walters, Daryl Murphy