Petrov, 26, a key part of Celtic's midfield since 1999 and the Bulgaria captain, said: "I need to move on and I hope Celtic respect my wishes." Celtic quickly rejected the request, while Petrov, who recently signed a contract to stay at Parkhead until 2009, has voiced a desire to play in England.
Celtic's manager, Gordon Strachan, said: "It might be a worry that this could have an effect on the player and those around him. But, despite him wanting to move on, we are relaxed about it. You are talking to someone who asked Alex Ferguson for a move [when at Aberdeen] and I was told to go forth and multiply. I was there the next two years, won a few more trophies and just got on with it."
With Rangers still stuttering for form, Hearts could all but wrap up second place with a win this afternoon in the Edinburgh derby against Hibernian at Easter Road - which would mean Gretna playing European football next season regardless of what happens in the Scottish Cup final next month.
Hearts are five points clear of Rangers this morning with four games to play, having won three of four meetings against Hibs this season (4-0, 4-1 and 4-0). Rangers have played Celtic four times this season, and have lost the last three.
Rangers' woes are compounded by Ferguson's long-term ankle problem. Alex McLeish will also be without Hamed Namouchi (ankle), Peter Lovenkrands (hip) and Fernando Ricksen (toe) for his last Old Firm game as the Rangers manager.
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