The Turkey international, who joined Stoke City last August for a fee believed to be around £6m, claims he is owed £544,677 for sporting and economic rights, and image rights.
The report maintains that two High Court actions relate to money which was unpaid during Tuncay's spell with Boro. Sundew Trading Ltd is claiming that Boro have paid Tuncay only £3m of an agreed £3,544,677 for the rights.
Agent Mikel Eiguren Arano has also produced a writ against Boro for £400,000 plus interest from money owed to him following Tuncay's move to the Teessiders from Fenerbahce in June 2007.
Arano was reputedly paid £800,000 of an agreed fee of £1.2m for helping facilitate Tuncay's free transfer from the Turkish club.
Boro paid an initial £400,000 to the agent in August 2007 and a further £400,000 12 months later but his claim details that he has not received the final payment.
Tuncay was in action last night, scoring in Stoke's 1-1 draw at Burnley.
Source: Northern Echo
Source: Northern Echo