Switzerland captain Alexander Frei claims Celtic have resurrected their interest in signing him.

The 28-year-old was ruled out of Euro 2008 after suffering a knee injury during his side's opening defeat by the Czech Republic.

But the Borussia Dortmund forward will be fit again in six weeks and he has told Celtic 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.