It is understood that PSG, who will face Rangers at Ibrox in the UEFA Cup in nine days' time, are keen to sign the 26-year-old.

Head coach Luis Fernandez has instructed his backroom team to establish whether Agathe would be willing to quit Parkhead for Paris, a move which could be construed within Parkhead as an unwelcome and illegal 'tap'.

And contact has been made with sources close to the Reunion-born player, who had an anonymous spell at Montpellier before resurrecting his career in Scotland.

Agathe collected three medals in his debut season at Celtic, having moved from Hibernian for the bargain-basement sum of £35,000 in October 2000.

His worth to the SPL leaders was underlined when he was awarded a lucrative new five-year contract on improved wages during the summer.

And O'Neill described the former Raith wing-back as having progressed to a '£29m' player after a stunning performance in the Champions League win over Rosenborg at Parkhead last month.

Agathe, who holds a French passport, has cherished ambitions of establishing himself in the French League before the end of his career.

PSG, marooned in mid-table ahead of the meeting with Rangers, are seeking a replacement for Laurent Robert, who ignored overtures from Rangers to follow David Ginola's path from PSG to Newcastle last summer.

Agathe, while normally operating on the opposite flank to Ginola or Robert, is viewed as a potential line of supply for Nicolas Anelka and Ronaldinho.