The Turkish giant is in discussions regarding a possible deal for the Nigeria international as new Blues boss Jose Mourinho looks to overhaul his squad
The Nigeria international has made over 277 appearances for Chelsea since arriving at the club back in 2006 in a protracted transfer saga involving Norwegian side Lyn and Manchester United.
However, speculation has mounted in recent weeks that the 26-year-old could be allowed to leave Stamford Bridge as Jose Mourinho sets about reshaping his squad in his second spell as manager.
"We are interested in Mikel, and negotiations are under way," Aysal told Sabah.
Mikel is on an extended break after competing in the Confederations Cup but was non-committal when questioned about his Stamford Bridge future earlier on Tuesday.
Chelsea has also been linked with other midfielders that could replace the Nigerian at Stamford Bridge, with Roma midfielder Daniele de Rossi and Vitesse youngster Marco van Ginkel both on the west London club's radar.