The centre-back has been offered a two-year deal by Turkish club Kayserispor, and is available for free transfer after failing to feature under Owen Coyle at Bolton this season.
Shittu went to Turkey earlier this month to look around the club and is currently weighing up the £1million-a-year contract offer, but insists his primary focus is on his national team commitments for South Africa this summer.
"It's good to see what clubs have to offer so I'm glad I went but I'm in the Nigerian World Cup camp just now and that's all I'm really thinking about," Shittu told the Daily Record.
Out-of-contract Rangers star Kris Boyd has also been in talks with Kayserispor's boss, ex-Gers striker Shota Arveladze, over a possible deal.
And Shittu has urged any potential signings to make the same trip he did and see what the club have to offer first-hand.
"Kayserispor have a nice stadium and the training ground is very good with top facilities," he added. "Everything about the club was very positive and I wouldn't put players off going out to see it for themselves."