The Turkish agent is asking for a fee worth €3 million and a watch.
According to SportBild, Calhanoglu has been told to meet in court over a dispute with the former agent.
With respect to the legal battle, Bektas is demanding for a watch as a pledge to make sure the payment arrives in due time.
Calhanoglu is currently working with Gordon Stipcic who played a key role in his transfer to Inter as his agent after parting ways with Bektas.
Calhanoglu, who has capped 64 times for Turkey, is expected to be in action when Inter Milan host Udinese in the Serie A on Sunday at the San Siro Stadium.
The versatile forward has scored once in the Nerazzurri shirt so far, providing three assists in eight Serie A games for Simone Inzaghi’s men.
Calhanoglu, born in Mannheim, Germany, joined Inter Milan from City rivals AC Milan on a free transfer, penning a three-year contract with the Nerazzurri.
The Turkey international has featured for a host of German clubs including Bayer Leverkusen, Hamburg among others.
Inter Milan, having won the Serie A title last season, are poised to defend the accolade and are third on the table with 21 points in ten games.