The 31 year old has not played since 2012, but has been given the chance to resurrect his career with a two year deal
Celtic live updates
Roy Keane has "asked not to be considered" for the vacant managerial position at Scottish champions Celtic.
The Republic of Ireland assistant manager has ruled himself out of the running to replace Neil Lennon, preferring to continue his work alongside Martin O'Neill.
Dermot Desmond, the Hoops majority shareholder, held talks with the former Manchester United skipper last week but it is understood the discussions did not get as far as a formal job offer.
A source close to the club told Press Association Sport: "Roy was not offered the job - no-one has been offered it yet.
"But he has ruled himself out and asked not to be considered for the position."
Celtic chief executive Peter Lawwell has confirmed the club are interested in appointing Roy Keane as their new boss.
But the Hoops chief says the Republic of Ireland assistant manager faces competition from as many as nine other rivals to be named Neil Lennon's successor.
Former Celtic team-mates John Hartson and Stiliyan Petrov carry the SPL trophy up Celtic away ahead of today's match against Dundee United