John Hartson believes Aiden McGeady will leave Celtic this summer.

McGeady has been linked with a lucrative move to Spartak Moscow - who recently had an £8.3million bid rejected - while Aston Villa and Birmingham are also reportedly interested.

Former Celtic striker Hartson insists last season, in particular, saw McGeady fail to make as much of an impact and that he could find himself with the option to move on if the price is right.

Hartson said: "Aiden has dipped in his performances over the last couple of years. Earlier on in his Celtic career he was absolutely phenomenal.

"He had problems with Gordon Strachan and his performances have dipped for such a great player.

"Maybe the club will look at that and may look to cash in on him, but he is a very important player for the club. He is one of the top players there and I'm sure they will discuss it at board level and decide what to do with Aiden.

"He wasn't as influential last season for sure as he has been in previous seasons so they may look at that."

Asked whether the time is right for him to go, Hartson added: "I can't say that. He's a young boy and he will make his own decision along with his advisors.

"All I know is, when Aiden McGeady is playing well, Celtic are a better side for it."