Bulgarian side CSKA Sofia have filed a lawsuit against Manchester United in relation to unpaid sell-on fees owed by the Old Trafford club following the transfer of Dimitar Berbatov from Spurs in September. Berbatov completed his protracted move to the Premier League Champions in the dying seconds of 2008’s summer transfer window, after a summer of speculation and wrangling between United and Spurs. The North Londoners were left feeling aggrieved with what they perceived to be an arrogant approach to negotiations from United. The unpaid fee, reportedly one million Bulgarian leva, roughly £450,000, was owed to Sofia after the £30.75 million transfer of the Bulgaria star to Old Trafford triggered a clause decreeing that CSKA be paid a percentage of any deal that saw Berbatov leave Tottenham. In usual circumstances any sell-on fee is paid by the selling club, in this instance Tottenham, however in Berbatov’s case it seems it may be the buying club picking up the bill. The two parties are said to have met on several occasions to settle the dispute, but Sportal has reported that United have said that "nothing will be wired to CSKA Sofia." CSKA have now taken the matter up with FIFA, and have recruited international sports lawyer Ian Blackshaw to present their case. Berbatov, 68 times capped by Bulgaria, left first club CSKA for Bundesliga side Bayer Leverkusen in 2001, from where he moved to Spurs for £10.75million in the summer of 2006.