CELTIC have rekindled their interest in Hearts" Bulgarian forward Branimir Kostadinov, with the player"s father claiming he has been asked to help arrange his son"s transfer to Parkhead.

Petio Kostadinov maintains Branimir is happy at Hearts but admitted no surprise at renewed interest from Celtic, who attempted to sign the player when he moved to Scotland in January 2006.

Kostadinov senior is a respected agent in his native Sofia and received a tentative inquiry about his 18-year-old son over the weekend, however he refused to become embroiled in negotiations.

"I received the call on Saturday and I was asked to help with the transfer of Branimir to Celtic," said Petio. "But I said this is not for me to discuss, they must speak with the owner.

"I am not surprised that Celtic have interest because they tried to sign Branimir before he went to Hearts. I was in Prague waiting to fly to Scotland and they called me at the airport and said when I get to Edinburgh I should go straight to Glasgow and not to Hearts.

"Stilian Petrov, who is like a son to me, called Branimir direct to try to take him to Celtic. But once he saw Hearts he said: "Dad, this is my club". I never say never in football but Branimir has a contract with Hearts."

Kostadinov was involved in Hearts Under-19s" 3-0 defeat by Celtic at Barrowfield on Saturday but has yet to appear for the first team. He has a contract at Tynecastle until 2009.