However, Celtic manager Ronny Deila wants to recruit the former Fulham youngster on a 12 or 18-month agreement, as reported by The Daily Mail.
Former Celtic midfielder and manager Hay has suggested that the Bhoys could do with someone like Roberts.
“I have felt throughout this window Celtic need players who will still be around come the Champions League qualifiers,” the former Scotland international midfielder has written in The Glasgow Evening Times.
“Getting through those summer matches lays the foundations for the season and so it would make sense to bring players in who can be bedded into the team by then.
“However, there is an argument Roberts could enhance the forward line and, given there is so much emphasis on Leigh Griffiths and the goals he brings to the team, then it might be an idea to have another player who can get in among the goals.”
“Unless Deila feels that it makes more sense to promote one of his own youth players, such as Aiden Nesbitt, there is a logical argument to say someone who can come in and weigh in on the goal front would be welcome,” added Hay.
Celtic do not need Roberts - or anyone else for that matter - this season, as their current squad is good enough to win the Scottish Premiership title.
What the Bhoys do need is quality and proven players who can help them in the Champions League qualifiers in the summer.
Roberts is talented and has a bright future, but would he be ready to make an impact for Celtic in Europe in the summer?