The player is a product of Farouk Khan's Stars of Africa Academy and it's believed he is eyeing a move to the PSL for the upcoming season.
He has been plying his trade for Swedish side IFK Hässleholm after leaving Khan's academy in 2010.
According to reports, he is currently on trial with the Free Staters under the watchful eye of coach Sammy Troughton.
Nkili started for Stars against Platinum Stars in a pre-season tournament, Maize Cup on Saturday morning.
The club is yet to confirm whether the central midfielder has signed or not.
Apart from Hässleholm, he also played for fellow Swedish side Orebro SK.
In addition, Stars are also looking at Ivorian striker Didier Lebri, who is also on trial.