Switzerland captain Alexander Frei claims Celtic are considering a summer move for his services.
The 28-year-old will miss the remainder of Euro 2008 after suffering a knee injury during his side's defeat by Czech Republic in the opening fixture of the tournament.
But the Borussia Dortmund forward is expected to be fit again in six weeks and has told Bhoys manager Gordon Strachan to make a move if he is interested.
"Apparently Celtic were in for me in 2004 and 2006," Frei said. "Now they want me again in 2008.
"However, no-one has ever put an offer on the table. If they want me they can phone me. Otherwise, I don't want to talk about it."
Meanwhile, out-of-favour Celtic defender Bobo Balde has been linked with a move to Birmingham.